the only way to accurately measure this is below. 1. use one car only, preferably with strong brakes. 2. get 4-6 different sets of tires and rims with different widths. 3. make sure tire hieght, brand and compound are exactly same. 4. run test several times per set of tires. 5. make sure the weather and temperatures are same. I can't think of anything else for controls. feel free to add
Amir Hussain I don't feel you need 4-6 different tire types. if I were to run the test I'd have 3 sets of identical rims for a vehicle. run 205s 225 and 245s of same tire (my old e36 bmw could take those 3 sizes). you should be able to see a corrolation if there is one. and to add a bonus fact I'd run the same sets on wet road to see if wider tires are worse for hydroplaning.
Amir Hussain I don't feel you need 4-6 different tire types. if I were to run the test I'd have 3 sets of identical rims for a vehicle. run 205s 225 and 245s of same tire (my old e36 bmw could take those 3 sizes). you should be able to see a corrolation if there is one. and to add a bonus fact I'd run the same sets on wet road to see if wider tires are worse for hydroplaning.
Yes I agree that this was not the best way to look into this because he totally disregards the diameter of the tire and the difference in the sizes of brakes
You're asking for lab conditions from a single engineer. The test isn't extremely accurate but the results are enough to conclude that tire width isn't the biggest factor in stopping distance, which is exactly what the experiment set out to do.
I agree that each science experiment needs a constant but in this case using multiple tires for a single car could be a bit difficult unless Jason has a tire company in his pocket lol
As an AP1 S2000 owner who got very confused looking at tires and rims I would like this. AP1 and AP2 have different staggered widths and then the possibility of a square setup on handling?
Ya, what about brake strength, ABS specifications, and tire slippage? Maybe low profile tires have more braking strength. So many variables, difficult to isolate to come up with sound conclusions. Limiting to one vehicle and just swap tires would be good.
There are so many other factors impacting a vehicle's stopping distance… brake - determines how long it takes for your wheels to lock up suspension, tyre compound & tyre pressure - determine how hard or soft your tyre profile is overall. Softer means more grip and therefore shorter stopping distance and vice versa You can only get some accurate correlation when all these factors are considered.
Some people aren't stoked - that's no good! What I enjoyed about all of this information is that it's not exactly what I expected to happen. Sure, there are different variables when every vehicle tested is a completely different car, but I found it fascinating how little correlation there was to a vehicle's weight and stopping distance. Quite surprising seeing the Nissan Armarda (6000 lbs) braking in the same distance as a Mitsubishi weighing 2700 lbs less. Also fascinating that tire width didn't strongly correlate with stopping distance. Even if the vehicles tested are different, you can see that clearly there are more important factors for stopping distance than weight or width alone. If you think the point of the video was to say that tire width and vehicle weight don't matter, that's not the case (as explained here: ruclips.net/video/kNa2gZNqmT8/видео.html). The point was that if you're planning on modifying your car, and think that you need bigger wheels and tires first to get better performance, you might want to simply check the rubber you're using first, and then worry about tire width. While you'll make marginal differences in grip with width and weight changes, you can make massive improvements with a good tire swap (my Honda S2000 increased peak longitudinal braking grip by 0.3 g's, that's insane!). Hope everyone's having a great day!
Don't try to please everyone, Jason. As your channel grows, you will have far more aggressive comments from people that want to harshly criticize you. Criticism, as you know, is good! I've been watching your channel since the second or third video, and I can tell you care for the comments. You care about what people say and you change a bit to make things better for us viewers. Don't mind those that judge the quality of video, because you will learn and improve off of some of their comments, as you always do. Great video again! I love the amount that I am able to learn from being a subscriber to you. P.S. I turn off my adblocker just for you :)
Engineering Explained Summer tire rubber compound would be the most important factor with tread pattern second (other than where tread has large holes or tiny tread blocks that deflect easiest with load). The traction rating of AS and A will include the combination of compound and tread block effectiveness in providing grip.
I think the data demonstrates that the engineers building these cars for the most part are putting on adequate brake, suspension and wheel size configurations to meet whatever minimum breaking distance safety standard they need to. The choice of a better tyre simply helps improve those results further.
This video is meaningless, You don't isolate any of the properties that you are testing. Testing different tire widths on different cars tells you nothing. To find if the width of the tires has any effect you should measure the change in stopping distance for the same car with different tires. Same goes for everything else.
Test one car, summer vs offroad vs all season tires. Same car, test all season narrow vs wider tires. See which change gives the biggest performance boost. Quicker, simpler, and more accurate.
Jason I like your video's a lot but this one (lets say) the least of them. Because of all the different parameters (cars, weight, surface, tyre manufacturer, tyre type, pressure, …) you found only very weak correlations. That was no coincidence. The best (imho the only meaningful) comparison was the performance on- and off-road. The Dodge performing about worst on-road and best off-road really says it all. I would love to see a video of you testing your Honda on different tyre widths! Thanks anyway for your awesome vids!
ya know the graph that shows weight/width to stopping distance? that normalizes the data to show exactly why width and weight don't matter nearly as much as compound and tire category. that's the whole point of the video. you don't need to isolate the variables to get to this conclusion. please take some math classes. all of you.
I remember learning in physics that the only two variables that are at play with friction are the coefficient of friction of the surface(s) and the downward force applied. It blew my mind. Theoretically, the size of the contact patch means nothing. I had a long discussion with my physics teacher about this and why wider tires increase traction on cars. Apparently there is so much more at play within the tire/pavement interface that it nearly nullifies the theoretical aspect of the equation. It was still interesting to learn that if tires had no tread, didn’t deform, and you were driving on a perfectly flat, hard surface, the width of the tire wouldn’t matter at all. A 5mm wide tire would work just as well as a 345mm tire given the same vehicle weight. It still doesn’t seem to make sense.
If a class spends the first week trying to convince students that they're as scientific as hard sciences, then it's not science. Every social science class ever.
Man I worked at a Biochemistry Lab for a while and my experiment needed an r^2 value of at least .95 or I had to redo it, but to be honest it was always above .98. But then again it was a simple experiment.
Despite some of the negative reactions I still think this was an interesting and enjoyable video. Now we know that tire compound is more important than width, it would be cool if you did a comparison with some vehicles with a fixed tire type but with different sizes, in width and diameter. starting from OEM and increasing the size till there are negative effects (because of higher weight, drag, price etc.). I look forward to that! Thanks and have a day! Greetings.
I've said it once, I'll say it again - this guy embodies everything that's great about RUclips. Unrivaled knowledge coupled with a natural talent for teaching... add to this the seldom-seen ability to include only what we really need to know, and what we have is an absolutely indispensable learning resource. The fact that, through RUclips, we get all that for free necessitates the burning question: why are we paying $$$$s for inferior quality tuition from college? Huge respect to EE!
I'm pretty sure stock brakes will outperform stock tires on most of the cars. If ABS is engaged during the emergency braking, then it means that brake applies more force than tire can handle, so it's the tire that is the limiting factor, not the brakes.
I petsonaly think this is one of the best way of explaining, better than whiteboard. Also if youake animations about new invensions it would be even better. Like laferrari's intake or so. Thums up from me.
He's said in the past why he doesn't use animations. For the most part it's because of the amount of time added to each video in order to get good quality animations vs how many videos he can put out using his white board. Plus it's kind of his thing now, why would we take that away?
It is clear tire type has the largest impact on stopping grip (on specific surfaces) but once you take this out there may be additional relationships to discover in the data. For example I suspect you will see a slope of close to 1 when plotting weight/width vs stopping distance for a single tire family. If so this would suggest several additional relationships: 1. Increasing the ratio of weight to width in general worsens dry pavement stopping distance and vice versa. 2. Increasing tire width (without changing anything else) improves dry stopping distance. 3. Reducing the weight of a vehicle shortens dry pavement stopping distance and vice versa. The above predictions align well with what we experience when changing tire size and driving on dry pavement BUT wet pavement and snow/slush covered roads are totally different (opposite conclusions are typical).
Awesome test! I would have liked to see tyre contact patch area and weight versus stopping distance. This would give more indication of how tire width and radius play into this.
There are way too many variables in these tests actual answers from experience: Do heavier cars have less grip? No they have more. (doesnt mean they stop faster) Do wider tires have more grip, in theory no, in actual life yes pretty much 100% of the time. Most important factor for tire grip? Tire compound.
Thank you captain obvious, zullok. If you watched any of Jason's other videos you'd know he knows all this and has educated us about that. If anything the title was a little misleading but I think it was meant to provoke thinking. Instead of finding out the obvious answer with five repeats over 25 different tires with the same car and suspension setup and tire pressure and outside temperature and .... Jason found out width isn't even half of the story. Active setup systems and tire compounds seem to account for most improvement in braking distance. This means that with the given (diverse!) real world data about cars in general he failed to reject null hypothesis. That is what you're supposed to take away from this video. He even goes out to point out the limitations of his dataset and I believe his numbers. If the actual research question was about tire width I'm pretty sure he would have used one of his other standard testing setups. I'm just overwhelmed by the number of people who took this for serious publishable research. Heck, he even says he doesn't know the weight of one of the vehicles he tested, why aren't people outraged about that if this is serious research?!
If your take is the true take away, then imho the name of the video should be "which of these stock cars stops better?"... but the data doesn't support that either as there are modified vehicles in the test. I think the precedent set in the early days of this channel means many of us expect well thought out experiments whether the results data is publishable or not. This seems to be more of a fleeting thought he acted on while at a cool event.
Luv'ya for using imperial units. Of course, it is not hard to mentally compute the conversion, but it's still a better experience to have both imperial and metric units on the graphs :) About the video, the topic and the measures: very well done! The common sens is finally backed up by a pretty accurate test :). If you guys live in a moderate/temperate climate you should use summer/winter tires, depending on the season AND the right tire pressure.
We tried this with a 91 mustang on a private test pad. 33 X 18.50 15 did not grip like 29 x 11.50 15. Same compound same day. 33s would break loose before the 29s would. Full contact patch was verified during the burnout and pressures were changed as needed. It came down to suspension set up, weight transfer weight over the tires. You have to have the weight in the right place to get the grip.
Wow. So many commenters here who seem to think they are very intelligent completely missed the point of this video. I'm going out on a limb here to say that Jason's goal in creating this video was not to create the ultimate tire test. It's possible he doesn't have the resources to conduct the comprehensive tire test some of you think he should have done. In addition, many comprehensive tire tests have already been conducted and he has nothing to gain by duplicating them. He had an opportunity to participate in a limited driving test of 27 vehicles. Instead of presenting the same boring feature comparison that all the other dozens of reviewers undoubtedly did after the event, he chose to stand out as different from the average reviewer by recording a limited amount of data and showing us how to draw useful conclusions from it. I learned a lot more from this video than I would have from a traditional auto review. I'm subscribed to this channel because of this unique perspective. Thank you for the work you did on this video.
Well if the point of this video is to answer the question that is contained in the thumbnail than no this video and all this data that was compiled is failing at answering said question. If you are simply asking if wider tires have more grip you would not be testing different types, sizes, brands, compounds, and cars. There are way too many variables that are changing from test to test. While this video gives some good information especially toward the end this video is not a good test for the stated question that was initially imposed. The data is certainly not bad but does not really correlate to the question that was posed. "So many commenters here who seem to think they are very intelligent completely missed the point of this video" Seems to me they aren't missing the point of the video if the point of the video was to answer the question in the thumbnail. Seems to me this video needs to be titled differently for that's not what was really tested through the parameters of this experiment.
To me it's kind of like this: Think about an electronics publication. Say they have 5 computers that they used a day each. They decided to perform hard drive benchmarks from within 5 different operating systems. They then use the data from the different tests on the hard drives to comment on the speed of the whole computers. It's related, sure. But the relation is loose and the expirement didn't provide enough data to really prove anything.
I strongly agree with 'optionedup' that Jason is presenting some very useful information & data, and I appreciate Jason's work on all of this..!! But I also agree that to answer the specific question, all of the testing should have been done on a single vehicle, or maybe a group of 3 -- street, all-season, and off-road -- to show how vehicle design/structure also effects braking efficiency. Otherwise, you can't 'isolate' width as the differing factor. Does a 265 tire on the BMW stop faster than a 235 tire? and so on.
You just gave the conventional wisdom of things I've been told by my dad all my life, and he is a mechanic! Great videos. You're the only guy I would want to give me car advice. Thanks alot!
In central/northern Europe, as well as in alpine regions, everybody uses summer and winter tyres. Only total cheapskates use all season. All season sucks in all seasons and is just marginally better than winter tyres in summer or summer tyres in winter. In the US, everybody apparently uses all season (which explains these comedy videos with cars sliding all over the place on icy roads), and I don't really get why. It's not like you're saving anything - sure, with winter/summer you have two sets of tyres, but they last twice as long. You need two sets of wheels, but they don't have to be alloys (lots of people use steel for winter tyres). You can have wider, grippier tyres in summer and narrower ones in winter, which don't suffer that much from aquaplaning and work better in snow and sludge. Also, you'll have a vastly superior performance in any season, and a huge advantage for your safety. AND you'll have a whole lotta more fun. Good tyres are the MOST important performance mod you can do for your car, and it's not expensive either.
@@BirdiesGoCherp I'm sorry but that is just not true. I wouldn't be talking like this if I did not know. OF COURSE i have checked out tyre reviews - most importantly the ones of the European car clubs. They do very thorough joint annual tyre reviews, both for summer and for winter tyres. And obviously their loyalty does not lie with suppliers or manufacturers but with their members only. They also do all-seasons, though I believe not regularly. Every time, the result is horrible. Some of them deliver performances almost on par with summer or winter tyres - the key word here is "or". Either one or another, but never both. Essentially, they are either summer tyres with a bit of snow-going capabilities, or winter tyres with a bit of summer rubber compound and a summer-ey thread profile. The better they are in summer, the more they suck in the winter and vice versa. Some of them offer a balanced performance, which actually is just another way of saying that they're equally horrible in both seasons. Whichever type you get, the one common thing they all have is that even the best performing ones for either seasons are never nearly as good as even mediocre summer or winter tyres. You can't cheat physics. The verdict of the tests is always the same: buy summer or winter tyres instead. If you don't have money, get the cheapest ones, they cost less than the non-horrible all seasons, perform better in both seasons, and last at least twice as long. They couldn't think of a good reason to use all-seasons, except that if for some unfathomable reason you MUST drive the same set of tyres all year round. And neither can I. Sure, to prevent fatal accidents, most people won't need the highest performance from their tyres most of the time. Until they do.
@@BirdiesGoCherp not disputing that. They might even be just as good as mediocre winter tyres, because in essence that's what they actually are - winter tyres made slightly worse. The dry performance is going to totally suck, I could almost bet. I was not conteding that all-seasons were TOTALLY useless for everything, just that they're vastly inferior to a summer/winter combination in almost any measure - cost, performance, longevity etc...
This seems really interesting Jason! I feel like doing some statistical tests on the dataset myself. Thanks for including your test results in the video!
I imagine the answer is "obviously yes", but noting that "just because a car has wider tires than a different car, doesn't mean that's the only determining factor" (especially of braking distance). If every car had the same tire design and compound, and if the braking test was performed with narrow and wide tires, the braking would be better with likely no exception.
hey ! engineering explained instead of plotting so much data try Buckingham theorem which will assist you in plotting a particular quantity vs another......have a nice day
"Do wider tyres have more grip?" *Tests with different vehicles including their weight rather than having one vehicle and testing with differ tyre widths and compounds.*
Two very simple modifications would provide a ton of insight - 1. Divide tire width by weight (mm/lbs), not the other way around (lbs/mm). 2. Plot the weighted width on the x-axis and the stopping distance on the y-axis. The plot should read - "given a tire width (corrected for weight) what was the sample's stopping distance?" then look for a trend. Also, since you know the different tire types, you may want to calculate separate regressions for each type. Of course, I get your point. (Spoiler!) The type of tire is more important than the the width. And you can only get that across by showing the different types on the same plot.
The point of this video isn't to give a complete picture with statistically significant conclusions, it's mainly to show that there are plenty of misconceptions about the topic. He's already done case studies showcasing modern technology in improving braking distances, so he just had some fun with raw data and extrapolating what he could.
Well, you have applied really poorly the OLS Estimator. It is obvious that when, for example, you estimate (brake distance) = α + β*(tire width) + error, that error term contains for example weight that has great correlation with your regressor, ie tire width (it could be not only weight! Everything contained in error term, that has good correlation with your regressor could have the same effect: like for instance brake size, that you did not measure). So you do not have the most important assumption required to use OLSE: strict exogeneity; that is that in y=α+βx+ε, Ε(εi | all x's)=0 for all i. Not only your results have poor R^2, but, because of this, they are also completely meaningless. Just waste. (NOTE: some results had R^2 like 0.14? These don't even worth to be shown, even if you had ensured the validity of OLSE assumptions) You could use at least a multi-variable regression like: (brake distance) = α + β1*(weight) + β2*(tire width) + ε, for example. This way you extract the effect of weight in error to a new additional factor, so ε gets cleaner (not guaranteed clean enough though; check "omitted variable" problem for further info). Your outcomes would become stronger in R^2 and more serious. You have a great channel, and I appreciate it very much. I am telling this in really good faith, as a more statistics educated person. Hope my intentions will not be missapprehended. :-)
You're watching an engineering video and you are concerned about units of measure...? Do you also want him to have this video translated into 27 different languages for you?
SI units are the standard in engineering. Better not do the same mistake like the Mars Climate Orbiter. While NASA used the "International System of Units" (SI units using metric system), the navigation software made by Lockheed Martin used the outdated imperial system. No conversion was made, the space probe approached Mars to much (by around 100km, calculate in miles on your own) and the probe got destroyed. Would not happen if engineers would have used the standard units of engineering in the first place. But that's none of my business. As a European I don't pay taxes that financed this disaster. Plus, this channel is Engineering Explained, and yet no usage of SI units.
I love how you do engineering measurements just for fun. There are some mistakes on statistical calculation but I did enjoy your presentation. It didn't give me the most accurate data but I think it's a good preliminary study to give general view of this matter. I think it would be a great pleasure for having you as a guest lecturer in Institut Teknologi Bandung (my uni) LOL
Hey Engineering Explained, love your videos. Your videos inspired me to pursue engineering. You always bring so much insight and engineering knowledge into your videos, it’s great! Could you do a video on wider tires specifically on snowy or slushy conditions. Would this be similar to the off road stopping distance results?
MyRealName I'm an engineering student and every company in the United States as well as American companies in foreign countries use imperial system so if you want to attend engineering courses in the U.S. Or work for U.S. Engineering firms, u must know the imperial system...you are mostly taught metric system in other courses like physics and chemistry courses and a mixture of metric and imperial in engineering courses
Hightower I agree the metric system is a lot easier to compute with, however I find that I can visualize the imperial system better, for example I have a better idea on what a mile looks like than a km, I can visualize how fast 60 mph is but not really 60 kph
The shame is yours. As an engineer, you should be able to proficiently and accurately use any unit system, any scale, anywhere, anytime, for any reason or any specification. He used what was available as mentioned in the video. I really do not believe he is auditioning for a job world wide.
A couple things: 1. R squared isn't the best number to look at for determining whether the relationship is statistically significant. A t-test in the Excel regression command would have been better. R squared values of 0.4 are pretty darn good for cross sectional data. 2. A regression of stopping distance on *both* weight and tire width would have told you if either of those factors mean something. You could also control for tire type with dummy variables. It would be great if you could provide the data for us to download!
In a single variate regression, don't expect T-student test of the single regressor and F-test (R^2) to give different outcomes... Also, R^2 of 0.4 could mean bad or good fit, depending on the model... But a magnitude of R^2=0.14 is bad fit. Here the problem is other, and it is more serious. We have obvious violation of exogeneity... (omitted variableS problem). So your second advice is towards the right way.
Asked this question to my physics teacher about 11 years ago, never got an answer then, but he did tell us that the formula for friction doesn't depend on area of contact (because molecular level contact can't really be calculated) instead it's dependent on load and on coefficient of friction (i.e type of tyre) while this data seems to be in relation to that I later found out that the width of the tyre is important during turns.
I am sure you can make grafs with metric units parallel to imperial... at least for weight unit Mini Cooper?? Cooper is trim level not model. Thanks for the video
College physics kid here, trying to act smart but what i have learn is that for Force of friction (dry friction) Ff=µ*Fn, where µ is the coefficient of friction (depends on the materials-in this case rubber in tires and asphalt) and Fn is the normal force (in this case its mass*gravity) and by that you can come to the conclusion that the amount of surface between the asphalt and tires doesn't impact the force of friction, but the weight does, but you could ask why don't heavier cars stop faster? It's because that mass also impacts the impulse of the car which just nullifies with friction (in most cases). English is not my native language so i excuse myself if you spent time reading this and didn't understand a thing
Back in the 1980s one of the Australian car mags did tests with various widths on the same set of vehicles. What they found was that wider tires give better grip "up to a point", but when they lose grip it's harder to recover it. Tire pressure is also important The stopping distance didn't really change much, but it mattered when cornering.
Any test braking a car on dry tarmac and upgrading its tire width testing again, all the other componts remaining the same, makes your theory false. And the F1 cars of 2017 where all the drivers are ultra-excited about much less stopping distance vs the 2016 season cars. Even with harder compounds the grip from the wider tires is greatly improved, especially when braking.
Thats not completely true. In a tire you have more forces then just the friction between the tire and the road. at first you have cohesion, wich means the tire is going to be deformed by the road on a small scale. Imagine little bits of the road pressing into the tire, thus creating more grip (and even more if your tire is wider). The second force you have to take into account is adhesion, wich are little bonding forces on a atomic level. They are also increased with wieder tires. trust me i'm an engineer
It would have been interesting to see what the R-values of the trend-lines would have been had you removed the upper and lower outliers from the calculation. That Ram PowerWagon and the BMW slewed the line dramatically.
Years ago Road and Track Magazine posted an article about tires ... the conclusion was wide tires have a shorter front to back footprints while narrower tires have a longer front to back footprints. The tires were driven over a glass panel and photographed from the bottom looking up at the rubber. The photos revealed that the surface area of 'rubber on the road' for wide or narrow tires is the same square cm on vehicles of the same weight.
Do narrower tyres have more grip? Yes, because of bigger pressure on the road. Case closed. When you take your argument and my argument into consideration, you will find out that it actually doesn't matter, and there are many more important factors that will determine grip, like tyre wear, tyre compound, tyre thread type and so on.
Bazsa Largely because the wider the tire, the softer you can make the compound without it collapsing the sidewall. The actual contact patch doesn't affect grip directly because friction is directly proportional to the normal force (i.e. the small the contact patch the higher the normal force and so the resulting friction is exactly the same, all else barred.) The size of the contact patch -does- affect wear, but not grip directly.
+Bazsa Wider tires are better for dry and sometimes light rain conditions. Skinny tires provide more grip in the snow and heavy rain where puddles form on the road. Then there's off road where the arguments never end, but skinny is typically better for shallow mud/snow while deep sand requires a wider tire, and the rock crawlers will argue all day long between wide vs skinny.. Wider tires are worse on fuel economy which could also be a factor depending on the situation. In races where different tire sizes are allowed, a car with less grip and skinnier tires could actually win against a car with better grip due to less pit stops etc. Everything's subjective.
Narrow tyre is better in shallow snow, but in deep is wider tyre better because it doesn't sink that much. If vehicle sink through snow too much, it starts to plow too much snow with a bumper which slows it down and finally stops it completely. Wider tyres make vehicle to "float" over the snow better.
I think tire pressure could have been interesting to see (while difficult to do at an event like this). I think the shape of the contact patch might have been more important than the actual width of the tires. Perhaps a test for the S2K?
Since the comments mentions a lot of what I wanted to say already, I'll just add this since I didn't see this in the comments that I seen: fix your axis. X is independent and y is dependent. Stopping distance is a dependent variable and should be on the y axis.
Wow , that's a lot of data to compile, thanks for sharing. The final conclusion, that tire type has a bigger impact on grip, than wider tires, or vehicle weight, seems reasonable. I think the title of the video " Do Wider Tires Actually Have More Grip? " was difficult , if not impossible to determine, due to the conditions of the testing, as also commented on below, however you did an excellent job of compiling and interrupting the data, and offered insightful conclusions.
Engineering Explained, I called a local Utah court today and there was a familiar voice on the other line while the intro played. Just found it rather amusing and had to share.
Having the slope of the wt/width vs stopping distance closer to 0 indicates a closer correlation of weight vs tire width. Interesting study dude thanks for the data!
Very good data and information, but another very important factor wasn't really mentioned. That is the vehicle's ABS programming. Some bad ABS program could increase your stopping distance vs a properly programed system. Another noteworthy factor is brake fade, which may seem irrelevant for an initial stop, but some smaller brakes could overheat by the end of the 60-0 stop as well, making them less effective by the end of the emergency stop and increasing stopping distance.
Weight distribution, suspension geometry, tire OD and sidewall profile, brake bias and environmental conditions would also have an effect on the results. A single vehicle test would be the only way to gather conclusive data. Still, very interesting results and another great video from EE.
Of course it does, but when you mount aftermarket rims and tires, you have to find optimal tire pressure for grip yourself. its quite easy, just measure if the tires have more heat in the middle or the sides of the tires and inflate/deflate accordingly. when the tire has the same temperature on the entire width of the contact patch, you have found your optimal tire pressure. (it may change a little with temperature, if its wet, etc, but you will get a good baseline.)
Been needing to change tires since you started talking about your S2000 crappy tires, since the car I bought came with winter tires and its getting hot. Finally decided and got a Michelin Pilot Sport 3 in 225 width, 20mm more than what it had 205. Man what a difference in stopping power! It feels like I have twice the grip I had before, love these tires.
Couple of points to add to what was discussed in the video: - Compound is critical as EE points out. And there is no compound or tread design that is the best at everything. BUT tire technology today is phenomenal compared to even 10 or 20 years ago. - Tire performance can change radically as the tire wears and how it is worn (shagging tires going sideways around a track for example) - Nearly every OEM tire is not the same thing you get from the tire store. In fact, where he pointed out 2 vehicles with the same tire: they are likely not the same. You need to look at construction code on the tire. Most OEM tires are tweaked to exactly the properties they want and can have different compounds or construction techniques. Occasionally, OEMs will take an existing construction code without changing it (i.e. a tire first created for Honda gets re-used on a Toyota). - Car manufacturers generally get the best tires (the most consistent based on specifications). The stuff you buy at the tire store are generally include a lot of the OEM rejects. I'm not sure about the tires if you buy them from a car dealer. - EE got about as accurate as you can given all of the variables floating around. In real tire testing, you have to do A/B/A tests (go back the control tire) so that you can estimate error over the period the testing was conducted. It is very hard to get an absolute performance metric for a tire, but you can see which tire has more/less of your desired attributes.
Usually, there's nothing worse than 'Death by Powerpoint' but this guy makes it work. So much knowledge - years of training and studying... and we get it back for free. Huge respect to EE!
Maybe in road courses, tire width really isn't all that important compared to compound. But let me tell you from a drag racing perspective. I'm worried less about stopping distance and a hell of a lot more about grip on launch. Now, I can run 11.5 in slicks on my car and I hook up pretty damn well. Compared to cars I've built before with 14 in slicks, I can notice a huge difference. More hot sticky rubber over a larger surface helps. Maybe not in road courses but it definitely holds true in drag racing.
What I learned at school, and on wikipedia, is that friction forces do not depend on contact surface (mathematically it does not, it is not just that the effects are neglectable); besides, for a same material, if you increase the vertical load, you will increase the horizontal force appliable before sliding. So I do not really understand the point of wider tires, from a grip point of view anyway (from a wear point of vieww, maybe it decreases wear...)
The short and hopefully easier answer to understand is this: Wide tires provide more surface area but also decrease surface pressure equally as you go wider. This would lead people to believe that width has little to no effect on grip but tires are mostly various types of rubber and silicone and also act as an adhesive. This means that while mechanically the grip should be relatively the same you have to account for the adhesion the rubber provides which increases grip as you go wider. Because there is a surface adhesion you now have to overcome the shear strength of the rubber to lose traction. Thats why when you lose traction your tire wears down. Leaving behind small pieces of rubber on the pavement. You didnt lose traction with the pavement, its actually so good that you lost the bond between the top most layer of your tire to the next layer. Remember ladies size matters! Al least on pavement!
Fogets that break type and breaking friction plays a roll. If you want the best breaking, then you get bigger disk breaks, wider tires, and softer compound on road, and bigger nobs off road.
Some people are saying that the test says that there's more to grip than the tyre width. Well, the question remains, if I have a certain car, with certain diameter tyres, I decided on a certain brand and type of tyres, should I get a narrower or a wider tyre? As far as I know both tyres have the same grip ideally, but narrower tyres have more contact pressure and so can deflect more and can dig deeper, and vice versa. So narrower tires are better for digging in shallow mud and snow, and for mechanical keying to a dirt or rock surface. For very soft surfaces like deep mud and snow and soft sand, wider tires are better to keep the car floating and not digging in. But then there's also the geometric aspect.
There is a correlation between tire width and weight. If the tire is too wide for the weight of the car, the vehicle will almost act like it is floating. Also putting a bigger tire on a lighter vehicle can cause you to have a odd tire pressure to maintain correct tire wear. The main thing to look at with tire size is the weight rating of the tires. If you put tires rated for a heavy vehicle on a small car, the car will bounce around. If you put too light weight of a tire on a heavy vehicle, the vehicle will sway and act like it has flat tires.
All the data makes me happy! Before you adjusted for weight, I was wondering if using weight per tire width units would give a more objective view, and then you did it!
Good statisticians hate the use of correlation coefficients in regression. Nor would they attempt to fit lines to data like that. If you removed the outliers the slope may even go the other way. Anyway you ended up with good conclusions. Keep different sets of tires for different uses!
I am concerned that you spread a lot of misleading information. For a test to be scientific, it MUST compare the SAME tire brand and model. Otherwise as proven by your data, your test is completely irrelevant! FACT: Coefficient of friction does not include contact area. This is absolute scientific fact. Do wider tires get better traction? They can but for completely different reasons than most people think. Here is how tires work: Rubber used on most tires today grip the road stronger than their ability to hold together. Try skidding your tires. If you have a soft tread, you leave rubber on the road. If you have a hard rubber tire, it leaves very little rubber on the road. In other words the tire gets better traction than its tear out strength. So, once you reach the threshold of where the rubber begins to tear off, you loose traction. Now, as the contract patch increases, you distribute the load over a greater area of the tire, which means the tire is less prone to tear out, or it takes more force to achieve tear out, as the force is distributed over a larger contact patch. The reality is, that for the tire manufacturer, they need to pick a tire where the tear out strength vs load is maximized for a given tire width. The manufacturers tend tend to error on the side of tire tear out, as it tends to be more forgiving. The rubber stretches as it tears, and tends to not loose grip abruptly. This allows the driver to have some control, even though the tire is sliding. Harder rubber tires tend to loose grip more abruptly, making them more dangerous. In the case of a heavy truck, the weight per square inch is several times what a car tire is. This means the rubber needs to be much stronger and harder, which it dramatically increases stopping distance. It also means when it does break loose, it is very abrupt and uncontrolled. So when you choose a tire, if you pick a softer compound, you should also switch to a wider tire. Simply going to a wider tire, may not increase traction, unless the tire is also softer, or your current tire leaves a lot of rubber on the road when you slide. Most wider tires are more likely to be sportier, and therefore are more likely to have a softer compound. Most people are going to make the right decision, but not really knowing why.
I think comparing SUV's and SUV's, Sedans vs. Sedans. trucks usually are out there on stopping distance because it is really obvious abuot the weight distribution. I hope you had a lot of fun
Friction is independent of surface area, purely wider tires do not decrease or increase stopping distance. Widening the tire allows softer and stickier rubber to be used mainly by decreasing the load on the sidewalls. Friction is determined by weight and the coefficient of friction where Friction=Coefficient of friction x Normal Force(usually the weight). You will notice that with this equation the force of friction increases linearly with the weight increase so the coefficient alone will determine the stopping distance for vehicles. The first scientist (Guillaume Amontons) to proclaim this was just about laughed out of the room until one of his peers proved him right. You can test it yourself if you have a force gauge and two building blocks tied together with a string. Do test 1 with both blocks on a table tied together, then do test 2 by stacking the second block on the first and repeat tug test (same weight half the surface area). They will take the same amount of force to move despite having the same weight and different surface areas. What really matters in a tire is what additives and rubber they are made of and how soft they are. Widening the tire reduces the load on the sidewall and decreases the rate of wear, allowing softer/"stickier" tires to be used. There you have it folks the secret to wide tires
Even though this was a very good comparison with a clear point and leaving out only information that is irrelevant for the point, I would have found it nice to include the following (especially as you will probably have a better understanding on its effects): Heavier cars obviously have more moving mass, which increases stopping distance, but they also have more grip due to the higher force pressing down on the tires. This could be interesting for the asphalt vs. off-road comparison, because from the data, it looks like generally, off-road traction matters a lot more than having low weight, so even though you have a heavy car that needs to lose a lot of energy to stop, the increased grip seems to have a larger impact, but on asphalt, it appears that having lower weight is a great advantage, perhaps because grip is quite good simply due to the nature of the surface. But maybe this is also irrelevant compared to the tires themselves, I honestly don't know. In any case, that's something I personally would have been interested in, but even though you did not include that, I still enjoyed the video very much!
There are so many factors that might influence this data I think Every car has ABS and it might be set on different brake forces which might influence stopping distance The ideal test would, intuitively, be a test where the wind is equal for all cars, the amount of aerodynamic drag they generate is known and taken into account, and they all apply the same total brake force for each brake (so front left has "150" (just an examplary number) force on all cars, and rear right "100"on all cars as well) This might give beter empirical evidence. A test where you ramp up the brake force to such a high number where all wheels would lock up might provide better insight as well After that, a test as to how much brake force you can put in the brakes before tires lock up I think that gives the most reliable data because I find this to appear a little too convoluted to really provide a solid answer
Great job. I like it very much! Actually tire grip depends heavily on the tread temperature in the contact zone and tread destruction. Wider tires means less pressure and hence less destruction, but less heating of the contact zone. That is why there is no linear dependency between tire width and grip.
Good video Jase, good data collection. Love your work as always, but please use metric units in addition to imperial. Also, just a production note for videos of this style, gotta edit out that swallowing bro, audio doesn't all have to be one take. Keep up the good work.
If load per tire is reduced when you increase surface area due to weight distribution then you need to find the balance between the cars weight and the width of the tire. You can increase tire load by adding a weight or adding aerodynamics to promote down-force which is fine if you are only concerned with braking or turning performance.
The only way to accurately make a correlation between tire width and stopping distance would require using the same vehicle under the same conditions of road surface, temperature and humidity and then vary the tire width on the vehicle using the same brand of tire as the tread pattern and tire compound will otherwise have a huge effect on the results. Even then, the aspect ratio of the tire, tire diameter and rotational inertia will play a role in the result.
Contact Patch!!! the width is only part of the equation. Disregarding the type of tire, larger side walls and tire diameter/circumference are the other parts of the equation to calculate contact patch.. After that is addressed then you can more accurately calculate PSI on the tire to the road. What I'm getting to is that you can have 245/45/R16 vs 245/35/18 which have the same width and diameter/circumference but the 245/45/R16 will have a larger contact patch because the side walls are 4.3in vs 3.4in. Same reason you will never see low profile tires on any real track car as it destroys the contact patch.
It would have been interesting to see how the front to rear weight balance affected the distances. Theoretically, moving weight towards the rear helps with grip on acceleration with rwd vehicles, so I would think moving it forward would help with deceleration. Still a great video, I know it must have taken forever to make and I'm not trying to sound unappreciative.
Before I even watch; it depends on the surface being driven on and the tire pressure. In snow, mud, etc, more narrow tires have more weight per square inch, which helps increase traction. However, on a normal paved road, the more tire that contacts the road (wider tires) the better the grip will be, assuming the pressure is not too high..
This is an interesting analysis based upon incomplete and imperfect data. I think the process of trying to extrapolate useful information when you don't have perfect data was the most interesting part of this video. One other thing that would be interesting to look at would be the effect of tire diameter on stopping distance.
+Engineering Explained I think instead of the contact area of the tires, you should consider the pattern of the tyres, and more importantly, the braking force/torque from the brake pad? It is the position where you slow down the car. The tyres undoubtedly affect the friction between itself and the ground, but the friction is only concerned when it comes to slip or not slip (gripping). Even the greater coefficient of friction should not be relevant to the stopping distance. How about do another test on the braking pad (although I have no idea how it can be done)? Very nice video concerning the fundamental issues. I have been very grateful to watch your channel. I was a mechanical engineering student but I learned more from you than my professors.
Tire width is only one factor, and it has more effect on the shape of the contact patch than the size of the contact patch. Suppose you have 4000 lb vehicle with 40 psi pressure in the tires. It will have 100 sq in of contact area, or 25 sq in per tire. Supposing said vehicle has 255 section width tires (approx 10 in width) then its contact patch would be approximately 10" wide by 2.5" long. Changing tire pressure or vehicle weight will have the biggest impact on the size of this contact patch. Changing tire width or overall diameter will change the shape of the contact patch more than the size. Tire width will have a much greater impact on lateral grip than on longitudinal grip. Run at the same pressure, a wider tire on the same car is going to have a wider contact patch, but shorter longitudinal dimension to have roughly the same area of contact patch. Similarly, going to a larger overall diameter, all else being equal, will increase the contact patch in the longitudinal dimension, offering more grip for accelerating and braking, though it will also have greater rotational inertia to contend with.
You should have included tire height in the final table. As you know, braking force at the tire/ground interface is a torque. Taller tires should stop longer, assuming same brake sizing, since the torque of the brakes is divided by a longer torque-arm due to the large tire diameter. To sum up my point, a 255/75/17 tire will take longer to stop than a 255/50/15. Same width, different diameter. I think a cornering test would have been more appropriate to determine if width affects grip.
12:20 this is why dual sport motorcycles have option to disable ABS for trails but motorcyclists are complaing about some companies that make ABS disabling harder for them or automatically come back while they are offroad and cause them to lose traction during technical riding
Oh my, there are so many variables that are unaccounted for to make a strong R. Tire comp and tread pattern, not to mention size. Without comparing different widths of the same tires across the different vehicles there seems to be very little to take away.
Wouldn't it be better to try and compare vehicles of a certain type? If you have a heavy SUV you might have a poor weight distribution during braking while a VW Alltrack most likely has a pretty good weight distribution during braking which should give it a huge advantage.
the only way to accurately measure this is below.
1. use one car only, preferably with strong brakes.
2. get 4-6 different sets of tires and rims with different widths.
3. make sure tire hieght, brand and compound are exactly same.
4. run test several times per set of tires.
5. make sure the weather and temperatures are same.
I can't think of anything else for controls. feel free to add
Amir Hussain I don't feel you need 4-6 different tire types. if I were to run the test I'd have 3 sets of identical rims for a vehicle. run 205s 225 and 245s of same tire (my old e36 bmw could take those 3 sizes). you should be able to see a corrolation if there is one.
and to add a bonus fact I'd run the same sets on wet road to see if wider tires are worse for hydroplaning.
Amir Hussain I don't feel you need 4-6 different tire types. if I were to run the test I'd have 3 sets of identical rims for a vehicle. run 205s 225 and 245s of same tire (my old e36 bmw could take those 3 sizes). you should be able to see a corrolation if there is one.
and to add a bonus fact I'd run the same sets on wet road to see if wider tires are worse for hydroplaning.
Yes I agree that this was not the best way to look into this because he totally disregards the diameter of the tire and the difference in the sizes of brakes
You're asking for lab conditions from a single engineer. The test isn't extremely accurate but the results are enough to conclude that tire width isn't the biggest factor in stopping distance, which is exactly what the experiment set out to do.
I agree that each science experiment needs a constant but in this case using multiple tires for a single car could be a bit difficult unless Jason has a tire company in his pocket lol
what about doing a test with one vehicle and several different tyre widths. (just need a tyre shop to sponsor)
Yep, would be great to do!
An interesting idea from a guy who stops his car with his feet.
As an AP1 S2000 owner who got very confused looking at tires and rims I would like this. AP1 and AP2 have different staggered widths and then the possibility of a square setup on handling?
fred flintsone that would be a true test
Ya, what about brake strength, ABS specifications, and tire slippage? Maybe low profile tires have more braking strength. So many variables, difficult to isolate to come up with sound conclusions. Limiting to one vehicle and just swap tires would be good.
There are so many other factors impacting a vehicle's stopping distance…
brake - determines how long it takes for your wheels to lock up
suspension, tyre compound & tyre pressure - determine how hard or soft your tyre profile is overall. Softer means more grip and therefore shorter stopping distance and vice versa
You can only get some accurate correlation when all these factors are considered.
Some people aren't stoked - that's no good! What I enjoyed about all of this information is that it's not exactly what I expected to happen. Sure, there are different variables when every vehicle tested is a completely different car, but I found it fascinating how little correlation there was to a vehicle's weight and stopping distance. Quite surprising seeing the Nissan Armarda (6000 lbs) braking in the same distance as a Mitsubishi weighing 2700 lbs less. Also fascinating that tire width didn't strongly correlate with stopping distance. Even if the vehicles tested are different, you can see that clearly there are more important factors for stopping distance than weight or width alone. If you think the point of the video was to say that tire width and vehicle weight don't matter, that's not the case (as explained here: ruclips.net/video/kNa2gZNqmT8/видео.html). The point was that if you're planning on modifying your car, and think that you need bigger wheels and tires first to get better performance, you might want to simply check the rubber you're using first, and then worry about tire width. While you'll make marginal differences in grip with width and weight changes, you can make massive improvements with a good tire swap (my Honda S2000 increased peak longitudinal braking grip by 0.3 g's, that's insane!). Hope everyone's having a great day!
Engineering Explained I liked it and it really does tell how important tyres are for your vehicle depending terrain and environment.
Don't try to please everyone, Jason. As your channel grows, you will have far more aggressive comments from people that want to harshly criticize you. Criticism, as you know, is good! I've been watching your channel since the second or third video, and I can tell you care for the comments. You care about what people say and you change a bit to make things better for us viewers. Don't mind those that judge the quality of video, because you will learn and improve off of some of their comments, as you always do. Great video again! I love the amount that I am able to learn from being a subscriber to you.
P.S. I turn off my adblocker just for you :)
Engineering Explained Summer tire rubber compound would be the most important factor with tread pattern second (other than where tread has large holes or tiny tread blocks that deflect easiest with load). The traction rating of AS and A will include the combination of compound and tread block effectiveness in providing grip.
how grip = stopping power?
I think the data demonstrates that the engineers building these cars for the most part are putting on adequate brake, suspension and wheel size configurations to meet whatever minimum breaking distance safety standard they need to. The choice of a better tyre simply helps improve those results further.
This video is meaningless, You don't isolate any of the properties that you are testing. Testing different tire widths on different cars tells you nothing. To find if the width of the tires has any effect you should measure the change in stopping distance for the same car with different tires. Same goes for everything else.
Different cars, different kind of tires (road tires vs off-road tires), ... This video is really bad.
Test one car, summer vs offroad vs all season tires.
Same car, test all season narrow vs wider tires.
See which change gives the biggest performance boost.
Quicker, simpler, and more accurate.
Jason I like your video's a lot but this one (lets say) the least of them.
Because of all the different parameters (cars, weight, surface, tyre manufacturer, tyre type, pressure, …) you found only very weak correlations. That was no coincidence. The best (imho the only meaningful) comparison was the performance on- and off-road. The Dodge performing about worst on-road and best off-road really says it all.
I would love to see a video of you testing your Honda on different tyre widths!
Thanks anyway for your awesome vids!
ya know the graph that shows weight/width to stopping distance? that normalizes the data to show exactly why width and weight don't matter nearly as much as compound and tire category. that's the whole point of the video. you don't need to isolate the variables to get to this conclusion. please take some math classes. all of you.
he is finding a trend
You did a very good job with the slideshow. Please don't ever do it again.
I remember learning in physics that the only two variables that are at play with friction are the coefficient of friction of the surface(s) and the downward force applied. It blew my mind. Theoretically, the size of the contact patch means nothing.
I had a long discussion with my physics teacher about this and why wider tires increase traction on cars. Apparently there is so much more at play within the tire/pavement interface that it nearly nullifies the theoretical aspect of the equation. It was still interesting to learn that if tires had no tread, didn’t deform, and you were driving on a perfectly flat, hard surface, the width of the tire wouldn’t matter at all. A 5mm wide tire would work just as well as a 345mm tire given the same vehicle weight. It still doesn’t seem to make sense.
hahahaha R=0.25 would be the wet dream of any psycological study
Haha yeah, my girlfriend's a biologist and said that 0.25 can be publishable. Fascinating haha.
R squared. Not R.
If a class spends the first week trying to convince students that they're as scientific as hard sciences, then it's not science. Every social science class ever.
Man I worked at a Biochemistry Lab for a while and my experiment needed an r^2 value of at least .95 or I had to redo it, but to be honest it was always above .98. But then again it was a simple experiment.
Pearson James yeah i study Biochem at uni! :) always a p
Why was Parker not invited ?
because Rob Dahm stole his invitation
And here I thought this was a drama free channel. 😂
no one is immune
Oscar Thorpe no replacement hood and akward apology = no invite to tire events
Because he was gonna bend their hoods not pay for it then insult them
Despite some of the negative reactions I still think this was an interesting and enjoyable video. Now we know that tire compound is more important than width, it would be cool if you did a comparison with some vehicles with a fixed tire type but with different sizes, in width and diameter. starting from OEM and increasing the size till there are negative effects (because of higher weight, drag, price etc.). I look forward to that! Thanks and have a day! Greetings.
Yes... very much agree...on all points... Informative video, and great suggestion for "Part 2".. (-:
I've said it once, I'll say it again - this guy embodies everything that's great about RUclips.
Unrivaled knowledge coupled with a natural talent for teaching... add to this the seldom-seen ability to include only what we really need to know, and what we have is an absolutely indispensable learning resource. The fact that, through RUclips, we get all that for free necessitates the burning question: why are we paying $$$$s for inferior quality tuition from college? Huge respect to EE!
You should actually make a video with your S2000 with wideass tires vs with oem tires
I thought the point of wide tires was cornering stability.
It helps the most with cornering, but also helps with lateral (acceleration and braking) grip.
Lateral refers to cornering.
Lateral grip = holding forces perpendicular to direction of travel
Longitudinal grip = holding forces parallel to direction of travel
Plot price of braking system against stopping distance please XD
I'm pretty sure stock brakes will outperform stock tires on most of the cars. If ABS is engaged during the emergency braking, then it means that brake applies more force than tire can handle, so it's the tire that is the limiting factor, not the brakes.
I petsonaly think this is one of the best way of explaining, better than whiteboard. Also if youake animations about new invensions it would be even better. Like laferrari's intake or so. Thums up from me.
He's said in the past why he doesn't use animations. For the most part it's because of the amount of time added to each video in order to get good quality animations vs how many videos he can put out using his white board. Plus it's kind of his thing now, why would we take that away?
It is clear tire type has the largest impact on stopping grip (on specific surfaces) but once you take this out there may be additional relationships to discover in the data.
For example I suspect you will see a slope of close to 1 when plotting weight/width vs stopping distance for a single tire family. If so this would suggest several additional relationships:
1. Increasing the ratio of weight to width in general worsens dry pavement stopping distance and vice versa.
2. Increasing tire width (without changing anything else) improves dry stopping distance.
3. Reducing the weight of a vehicle shortens dry pavement stopping distance and vice versa.
The above predictions align well with what we experience when changing tire size and driving on dry pavement BUT wet pavement and snow/slush covered roads are totally different (opposite conclusions are typical).
Well, this is good upload timing between our channels!
Awesome test! I would have liked to see tyre contact patch area and weight versus stopping distance. This would give more indication of how tire width and radius play into this.
There are way too many variables in these tests
actual answers from experience:
Do heavier cars have less grip? No they have more. (doesnt mean they stop faster)
Do wider tires have more grip, in theory no, in actual life yes pretty much 100% of the time.
Most important factor for tire grip? Tire compound.
example is the pressure of the caliper, the number of calipers, and the material of the rotors and pads.
Thank you captain obvious, zullok. If you watched any of Jason's other videos you'd know he knows all this and has educated us about that. If anything the title was a little misleading but I think it was meant to provoke thinking.
Instead of finding out the obvious answer with five repeats over 25 different tires with the same car and suspension setup and tire pressure and outside temperature and .... Jason found out width isn't even half of the story. Active setup systems and tire compounds seem to account for most improvement in braking distance. This means that with the given (diverse!) real world data about cars in general he failed to reject null hypothesis. That is what you're supposed to take away from this video.
He even goes out to point out the limitations of his dataset and I believe his numbers. If the actual research question was about tire width I'm pretty sure he would have used one of his other standard testing setups. I'm just overwhelmed by the number of people who took this for serious publishable research. Heck, he even says he doesn't know the weight of one of the vehicles he tested, why aren't people outraged about that if this is serious research?!
And what's the theory behind wider tires?
If your take is the true take away, then imho the name of the video should be "which of these stock cars stops better?"... but the data doesn't support that either as there are modified vehicles in the test. I think the precedent set in the early days of this channel means many of us expect well thought out experiments whether the results data is publishable or not. This seems to be more of a fleeting thought he acted on while at a cool event.
Djd34d1, ummm... yeah. If offered an opportunity like that, I'd jump on it and make something of it as well. I believe he implies as much also.
Luv'ya for using imperial units. Of course, it is not hard to mentally compute the conversion, but it's still a better experience to have both imperial and metric units on the graphs :)
About the video, the topic and the measures: very well done! The common sens is finally backed up by a pretty accurate test :). If you guys live in a moderate/temperate climate you should use summer/winter tires, depending on the season AND the right tire pressure.
We tried this with a 91 mustang on a private test pad. 33 X 18.50 15 did not grip like 29 x 11.50 15. Same compound same day. 33s would break loose before the 29s would. Full contact patch was verified during the burnout and pressures were changed as needed. It came down to suspension set up, weight transfer weight over the tires. You have to have the weight in the right place to get the grip.
Beautiful video. Good information. Totally answered things I had been wondering about. Thanks!
Wow. So many commenters here who seem to think they are very intelligent completely missed the point of this video. I'm going out on a limb here to say that Jason's goal in creating this video was not to create the ultimate tire test. It's possible he doesn't have the resources to conduct the comprehensive tire test some of you think he should have done. In addition, many comprehensive tire tests have already been conducted and he has nothing to gain by duplicating them. He had an opportunity to participate in a limited driving test of 27 vehicles. Instead of presenting the same boring feature comparison that all the other dozens of reviewers undoubtedly did after the event, he chose to stand out as different from the average reviewer by recording a limited amount of data and showing us how to draw useful conclusions from it. I learned a lot more from this video than I would have from a traditional auto review. I'm subscribed to this channel because of this unique perspective. Thank you for the work you did on this video.
+optionedup appreciate the thoughtfulness of your comment, glad you enjoyed the video!
Well if the point of this video is to answer the question that is contained in the thumbnail than no this video and all this data that was compiled is failing at answering said question. If you are simply asking if wider tires have more grip you would not be testing different types, sizes, brands, compounds, and cars. There are way too many variables that are changing from test to test. While this video gives some good information especially toward the end this video is not a good test for the stated question that was initially imposed. The data is certainly not bad but does not really correlate to the question that was posed.
"So many commenters here who seem to think they are very intelligent completely missed the point of this video" Seems to me they aren't missing the point of the video if the point of the video was to answer the question in the thumbnail. Seems to me this video needs to be titled differently for that's not what was really tested through the parameters of this experiment.
To me it's kind of like this: Think about an electronics publication. Say they have 5 computers that they used a day each. They decided to perform hard drive benchmarks from within 5 different operating systems. They then use the data from the different tests on the hard drives to comment on the speed of the whole computers. It's related, sure. But the relation is loose and the expirement didn't provide enough data to really prove anything.
I strongly agree with 'optionedup' that Jason is presenting some very useful information & data, and I appreciate Jason's work on all of this..!!
But I also agree that to answer the specific question, all of the testing should have been done on a single vehicle, or maybe a group of 3 -- street, all-season, and off-road -- to show how vehicle design/structure also effects braking efficiency. Otherwise, you can't 'isolate' width as the differing factor. Does a 265 tire on the BMW stop faster than a 235 tire? and so on.
You just gave the conventional wisdom of things I've been told by my dad all my life, and he is a mechanic! Great videos. You're the only guy I would want to give me car advice. Thanks alot!
+SvenStadt Your Dad seems like a good dude, great to pass down car knowledge!
braking system(rotors, calipers, pads) depends a lot on stop distance
That’s what i was going to post as well. Good to see someone did.
In central/northern Europe, as well as in alpine regions, everybody uses summer and winter tyres. Only total cheapskates use all season. All season sucks in all seasons and is just marginally better than winter tyres in summer or summer tyres in winter. In the US, everybody apparently uses all season (which explains these comedy videos with cars sliding all over the place on icy roads), and I don't really get why. It's not like you're saving anything - sure, with winter/summer you have two sets of tyres, but they last twice as long. You need two sets of wheels, but they don't have to be alloys (lots of people use steel for winter tyres). You can have wider, grippier tyres in summer and narrower ones in winter, which don't suffer that much from aquaplaning and work better in snow and sludge. Also, you'll have a vastly superior performance in any season, and a huge advantage for your safety. AND you'll have a whole lotta more fun. Good tyres are the MOST important performance mod you can do for your car, and it's not expensive either.
All season tyres are actual really good, shitty tyres are shitty. All seasons are very good, check out tyre reviews.
@@BirdiesGoCherp I'm sorry but that is just not true. I wouldn't be talking like this if I did not know. OF COURSE i have checked out tyre reviews - most importantly the ones of the European car clubs. They do very thorough joint annual tyre reviews, both for summer and for winter tyres. And obviously their loyalty does not lie with suppliers or manufacturers but with their members only. They also do all-seasons, though I believe not regularly. Every time, the result is horrible. Some of them deliver performances almost on par with summer or winter tyres - the key word here is "or". Either one or another, but never both. Essentially, they are either summer tyres with a bit of snow-going capabilities, or winter tyres with a bit of summer rubber compound and a summer-ey thread profile. The better they are in summer, the more they suck in the winter and vice versa. Some of them offer a balanced performance, which actually is just another way of saying that they're equally horrible in both seasons. Whichever type you get, the one common thing they all have is that even the best performing ones for either seasons are never nearly as good as even mediocre summer or winter tyres. You can't cheat physics.
The verdict of the tests is always the same: buy summer or winter tyres instead. If you don't have money, get the cheapest ones, they cost less than the non-horrible all seasons, perform better in both seasons, and last at least twice as long. They couldn't think of a good reason to use all-seasons, except that if for some unfathomable reason you MUST drive the same set of tyres all year round. And neither can I.
Sure, to prevent fatal accidents, most people won't need the highest performance from their tyres most of the time. Until they do.
@@horrovac their latest all season reviews show incredible performance in the wet and on snow though.
@@BirdiesGoCherp not disputing that. They might even be just as good as mediocre winter tyres, because in essence that's what they actually are - winter tyres made slightly worse. The dry performance is going to totally suck, I could almost bet. I was not conteding that all-seasons were TOTALLY useless for everything, just that they're vastly inferior to a summer/winter combination in almost any measure - cost, performance, longevity etc...
Screw the data! I am going to slap on some 315's all seasons for my stock 8th gen civic! Burn rice baby! 🔥🍚
Horacio Lopez 8th Gen Civics ftw
stick brembo decals to the calipers, it'll greatly improve the breaking distance on your rice. Trust me.
Stickers are +5 horsepower each!
that's not rice, that is how you get a ticket
add more water when cooking?
This seems really interesting Jason!
I feel like doing some statistical tests on the dataset myself. Thanks for including your test results in the video!
I imagine the answer is "obviously yes", but noting that "just because a car has wider tires than a different car, doesn't mean that's the only determining factor" (especially of braking distance). If every car had the same tire design and compound, and if the braking test was performed with narrow and wide tires, the braking would be better with likely no exception.
hey ! engineering explained instead of plotting so much data try Buckingham theorem which will assist you in plotting a particular quantity vs another......have a nice day
"Do wider tyres have more grip?" *Tests with different vehicles including their weight rather than having one vehicle and testing with differ tyre widths and compounds.*
Two very simple modifications would provide a ton of insight - 1. Divide tire width by weight (mm/lbs), not the other way around (lbs/mm). 2. Plot the weighted width on the x-axis and the stopping distance on the y-axis.
The plot should read - "given a tire width (corrected for weight) what was the sample's stopping distance?" then look for a trend. Also, since you know the different tire types, you may want to calculate separate regressions for each type.
Of course, I get your point. (Spoiler!) The type of tire is more important than the the width. And you can only get that across by showing the different types on the same plot.
The point of this video isn't to give a complete picture with statistically significant conclusions, it's mainly to show that there are plenty of misconceptions about the topic. He's already done case studies showcasing modern technology in improving braking distances, so he just had some fun with raw data and extrapolating what he could.
Well, you have applied really poorly the OLS Estimator.
It is obvious that when, for example, you estimate (brake distance) = α + β*(tire width) + error, that error term contains for example weight that has great correlation with your regressor, ie tire width (it could be not only weight! Everything contained in error term, that has good correlation with your regressor could have the same effect: like for instance brake size, that you did not measure). So you do not have the most important assumption required to use OLSE: strict exogeneity; that is that in y=α+βx+ε, Ε(εi | all x's)=0 for all i. Not only your results have poor R^2, but, because of this, they are also completely meaningless. Just waste. (NOTE: some results had R^2 like 0.14? These don't even worth to be shown, even if you had ensured the validity of OLSE assumptions)
You could use at least a multi-variable regression like: (brake distance) = α + β1*(weight) + β2*(tire width) + ε, for example. This way you extract the effect of weight in error to a new additional factor, so ε gets cleaner (not guaranteed clean enough though; check "omitted variable" problem for further info). Your outcomes would become stronger in R^2 and more serious.
You have a great channel, and I appreciate it very much. I am telling this in really good faith, as a more statistics educated person. Hope my intentions will not be missapprehended. :-)
PLEASE. Use METRIC.
AMERICA 1ST! EVERYPLACE ELSE IS THE WORST!
+rossi23 You'll be singing a different tune after Glorious Leader Trump starts WW3
Use a calculator. It isn't that difficult.
You're watching an engineering video and you are concerned about units of measure...? Do you also want him to have this video translated into 27 different languages for you?
SI units are the standard in engineering. Better not do the same mistake like the Mars Climate Orbiter. While NASA used the "International System of Units" (SI units using metric system), the navigation software made by Lockheed Martin used the outdated imperial system. No conversion was made, the space probe approached Mars to much (by around 100km, calculate in miles on your own) and the probe got destroyed.
Would not happen if engineers would have used the standard units of engineering in the first place. But that's none of my business. As a European I don't pay taxes that financed this disaster.
Plus, this channel is Engineering Explained, and yet no usage of SI units.
I love how you do engineering measurements just for fun. There are some mistakes on statistical calculation but I did enjoy your presentation. It didn't give me the most accurate data but I think it's a good preliminary study to give general view of this matter. I think it would be a great pleasure for having you as a guest lecturer in Institut Teknologi Bandung (my uni) LOL
Hey Engineering Explained, love your videos. Your videos inspired me to pursue engineering. You always bring so much insight and engineering knowledge into your videos, it’s great! Could you do a video on wider tires specifically on snowy or slushy conditions. Would this be similar to the off road stopping distance results?
I'd be ashamed as an engineer if I didn't use the universal metric system.
Plus you'll increase your world wide job chances as well by using the universal metric system.
MyRealName I'm an engineering student and every company in the United States as well as American companies in foreign countries use imperial system so if you want to attend engineering courses in the U.S. Or work for U.S. Engineering firms, u must know the imperial system...you are mostly taught metric system in other courses like physics and chemistry courses and a mixture of metric and imperial in engineering courses
we use both. and yes every engineer that i know prefers metric.
Hightower I agree the metric system is a lot easier to compute with, however I find that I can visualize the imperial system better, for example I have a better idea on what a mile looks like than a km, I can visualize how fast 60 mph is but not really 60 kph
The shame is yours.
As an engineer, you should be able to proficiently and accurately use any unit system, any scale, anywhere, anytime, for any reason or any specification.
He used what was available as mentioned in the video.
I really do not believe he is auditioning for a job world wide.
SI units please
Why does it matter? The chart would look exactly the same.
FREEDUM UNITS RULE!!! America 1st!, Every place else is the worst!
A couple things:
1. R squared isn't the best number to look at for determining whether the relationship is statistically significant. A t-test in the Excel regression command would have been better. R squared values of 0.4 are pretty darn good for cross sectional data.
2. A regression of stopping distance on *both* weight and tire width would have told you if either of those factors mean something. You could also control for tire type with dummy variables. It would be great if you could provide the data for us to download!
In a single variate regression, don't expect T-student test of the single regressor and F-test (R^2) to give different outcomes... Also, R^2 of 0.4 could mean bad or good fit, depending on the model... But a magnitude of R^2=0.14 is bad fit.
Here the problem is other, and it is more serious. We have obvious violation of exogeneity... (omitted variableS problem). So your second advice is towards the right way.
Asked this question to my physics teacher about 11 years ago, never got an answer then, but he did tell us that the formula for friction doesn't depend on area of contact (because molecular level contact can't really be calculated) instead it's dependent on load and on coefficient of friction (i.e type of tyre) while this data seems to be in relation to that I later found out that the width of the tyre is important during turns.
I've never had the highest likes on a comment
You got this, man!
and hopefully you don't get it on some like hungry comment like this.
HAHAHHAHA your name is hilarious!!
The spotlight is all you!
I am sure you can make grafs with metric units parallel to imperial... at least for weight unit
Mini Cooper?? Cooper is trim level not model.
Thanks for the video
denistablica except it was a Cooper. All Countrymen are Coopers, so he wasn't wrong. In fact, they are all Cooper S's
College physics kid here, trying to act smart but what i have learn is that for Force of friction (dry friction) Ff=µ*Fn, where µ is the coefficient of friction (depends on the materials-in this case rubber in tires and asphalt) and Fn is the normal force (in this case its mass*gravity) and by that you can come to the conclusion that the amount of surface between the asphalt and tires doesn't impact the force of friction, but the weight does, but you could ask why don't heavier cars stop faster? It's because that mass also impacts the impulse of the car which just nullifies with friction (in most cases).
English is not my native language so i excuse myself if you spent time reading this and didn't understand a thing
Back in the 1980s one of the Australian car mags did tests with various widths on the same set of vehicles.
What they found was that wider tires give better grip "up to a point", but when they lose grip it's harder to recover it.
Tire pressure is also important
The stopping distance didn't really change much, but it mattered when cornering.
Engineer using imperial? Blasphemy!
technically, physics wise, friction has nothing to with contact area
EDIT: yh that's not true
I wonder why so many people believe that wider tire means more grip.
Tire company conspiracy?
Any test braking a car on dry tarmac and upgrading its tire width testing again, all the other componts remaining the same, makes your theory false. And the F1 cars of 2017 where all the drivers are ultra-excited about much less stopping distance vs the 2016 season cars. Even with harder compounds the grip from the wider tires is greatly improved, especially when braking.
Theoretically yes, in real life not all materials behave this way. Watch his tire load sensitivity video.
Yh of course u can benefit from wider tires.. they're also more stable
On paper the friction is the same. just throwing it out there
Thats not completely true. In a tire you have more forces then just the friction between the tire and the road. at first you have cohesion, wich means the tire is going to be deformed by the road on a small scale. Imagine little bits of the road pressing into the tire, thus creating more grip (and even more if your tire is wider). The second force you have to take into account is adhesion, wich are little bonding forces on a atomic level. They are also increased with wieder tires.
trust me i'm an engineer
It would have been interesting to see what the R-values of the trend-lines would have been had you removed the upper and lower outliers from the calculation.
That Ram PowerWagon and the BMW slewed the line dramatically.
Years ago Road and Track Magazine posted an article about tires ... the conclusion was wide tires have a shorter front to back footprints while narrower tires have a longer front to back footprints.
The tires were driven over a glass panel and photographed from the bottom looking up at the rubber.
The photos revealed that the surface area of 'rubber on the road' for wide or narrow tires is the same square cm on vehicles of the same weight.
Do wider tires actually have more grip? Yes, because of a bigger tyre patch on the road surface. Case closed.
Do narrower tyres have more grip? Yes, because of bigger pressure on the road. Case closed. When you take your argument and my argument into consideration, you will find out that it actually doesn't matter, and there are many more important factors that will determine grip, like tyre wear, tyre compound, tyre thread type and so on.
If false then tell me why F1 cars have wide tires? especially this year...
Bazsa Largely because the wider the tire, the softer you can make the compound without it collapsing the sidewall. The actual contact patch doesn't affect grip directly because friction is directly proportional to the normal force (i.e. the small the contact patch the higher the normal force and so the resulting friction is exactly the same, all else barred.) The size of the contact patch -does- affect wear, but not grip directly.
+Bazsa Wider tires are better for dry and sometimes light rain conditions. Skinny tires provide more grip in the snow and heavy rain where puddles form on the road. Then there's off road where the arguments never end, but skinny is typically better for shallow mud/snow while deep sand requires a wider tire, and the rock crawlers will argue all day long between wide vs skinny.. Wider tires are worse on fuel economy which could also be a factor depending on the situation.
In races where different tire sizes are allowed, a car with less grip and skinnier tires could actually win against a car with better grip due to less pit stops etc. Everything's subjective.
Narrow tyre is better in shallow snow, but in deep is wider tyre better because it doesn't sink that much. If vehicle sink through snow too much, it starts to plow too much snow with a bumper which slows it down and finally stops it completely. Wider tyres make vehicle to "float" over the snow better.
This video is pointless.
USE METRIC!!!
I think tire pressure could have been interesting to see (while difficult to do at an event like this). I think the shape of the contact patch might have been more important than the actual width of the tires. Perhaps a test for the S2K?
Since the comments mentions a lot of what I wanted to say already, I'll just add this since I didn't see this in the comments that I seen: fix your axis. X is independent and y is dependent. Stopping distance is a dependent variable and should be on the y axis.
We need a stock vehicle tested with different tire widths and loads. Now that's a good test.
Wow , that's a lot of data to compile, thanks for sharing. The final conclusion, that tire type has a bigger impact on grip, than wider tires, or vehicle weight, seems reasonable. I think the title of the video " Do Wider Tires Actually Have More Grip? " was difficult , if not impossible to determine, due to the conditions of the testing, as also commented on below, however you did an excellent job of compiling and interrupting the data, and offered insightful conclusions.
Engineering Explained, I called a local Utah court today and there was a familiar voice on the other line while the intro played. Just found it rather amusing and had to share.
Heavier vehicles have more momentum and hence will be harder to stop hence larger stoping distance
Having the slope of the wt/width vs stopping distance closer to 0 indicates a closer correlation of weight vs tire width. Interesting study dude thanks for the data!
"This amazing sketch I did truly breathtaking" I literally laughed out loud!
Very good data and information, but another very important factor wasn't really mentioned. That is the vehicle's ABS programming. Some bad ABS program could increase your stopping distance vs a properly programed system. Another noteworthy factor is brake fade, which may seem irrelevant for an initial stop, but some smaller brakes could overheat by the end of the 60-0 stop as well, making them less effective by the end of the emergency stop and increasing stopping distance.
I got so exited @ 09:40 . and its from a boring slideshow.
great job Jason!
Appreciate the time and effort to show us your data and analysis.
Weight distribution, suspension geometry, tire OD and sidewall profile, brake bias and environmental conditions would also have an effect on the results. A single vehicle test would be the only way to gather conclusive data. Still, very interesting results and another great video from EE.
Of course it does, but when you mount aftermarket rims and tires, you have to find optimal tire pressure for grip yourself. its quite easy, just measure if the tires have more heat in the middle or the sides of the tires and inflate/deflate accordingly. when the tire has the same temperature on the entire width of the contact patch, you have found your optimal tire pressure. (it may change a little with temperature, if its wet, etc, but you will get a good baseline.)
I actually enjoyed the slide show pretty well. I'm shocked, keep up the good work !
Been needing to change tires since you started talking about your S2000 crappy tires, since the car I bought came with winter tires and its getting hot. Finally decided and got a Michelin Pilot Sport 3 in 225 width, 20mm more than what it had 205. Man what a difference in stopping power! It feels like I have twice the grip I had before, love these tires.
Couple of points to add to what was discussed in the video:
- Compound is critical as EE points out. And there is no compound or tread design that is the best at everything. BUT tire technology today is phenomenal compared to even 10 or 20 years ago.
- Tire performance can change radically as the tire wears and how it is worn (shagging tires going sideways around a track for example)
- Nearly every OEM tire is not the same thing you get from the tire store. In fact, where he pointed out 2 vehicles with the same tire: they are likely not the same. You need to look at construction code on the tire. Most OEM tires are tweaked to exactly the properties they want and can have different compounds or construction techniques. Occasionally, OEMs will take an existing construction code without changing it (i.e. a tire first created for Honda gets re-used on a Toyota).
- Car manufacturers generally get the best tires (the most consistent based on specifications). The stuff you buy at the tire store are generally include a lot of the OEM rejects. I'm not sure about the tires if you buy them from a car dealer.
- EE got about as accurate as you can given all of the variables floating around. In real tire testing, you have to do A/B/A tests (go back the control tire) so that you can estimate error over the period the testing was conducted. It is very hard to get an absolute performance metric for a tire, but you can see which tire has more/less of your desired attributes.
Usually, there's nothing worse than 'Death by Powerpoint' but this guy makes it work. So much knowledge - years of training and studying... and we get it back for free. Huge respect to EE!
Great data. Think Amir Hussain the comments addressed the better way of answering the question. Wish you would do that test also.
Maybe in road courses, tire width really isn't all that important compared to compound. But let me tell you from a drag racing perspective. I'm worried less about stopping distance and a hell of a lot more about grip on launch. Now, I can run 11.5 in slicks on my car and I hook up pretty damn well. Compared to cars I've built before with 14 in slicks, I can notice a huge difference. More hot sticky rubber over a larger surface helps. Maybe not in road courses but it definitely holds true in drag racing.
What I learned at school, and on wikipedia, is that friction forces do not depend on contact surface (mathematically it does not, it is not just that the effects are neglectable); besides, for a same material, if you increase the vertical load, you will increase the horizontal force appliable before sliding.
So I do not really understand the point of wider tires, from a grip point of view anyway (from a wear point of vieww, maybe it decreases wear...)
The short and hopefully easier answer to understand is this:
Wide tires provide more surface area but also decrease surface pressure equally as you go wider. This would lead people to believe that width has little to no effect on grip but tires are mostly various types of rubber and silicone and also act as an adhesive. This means that while mechanically the grip should be relatively the same you have to account for the adhesion the rubber provides which increases grip as you go wider. Because there is a surface adhesion you now have to overcome the shear strength of the rubber to lose traction. Thats why when you lose traction your tire wears down. Leaving behind small pieces of rubber on the pavement. You didnt lose traction with the pavement, its actually so good that you lost the bond between the top most layer of your tire to the next layer.
Remember ladies size matters! Al least on pavement!
A well documented guide to the advantages and disadvantages of different tire types !
Fogets that break type and breaking friction plays a roll. If you want the best breaking, then you get bigger disk breaks, wider tires, and softer compound on road, and bigger nobs off road.
Some people are saying that the test says that there's more to grip than the tyre width. Well, the question remains, if I have a certain car, with certain diameter tyres, I decided on a certain brand and type of tyres, should I get a narrower or a wider tyre?
As far as I know both tyres have the same grip ideally, but narrower tyres have more contact pressure and so can deflect more and can dig deeper, and vice versa. So narrower tires are better for digging in shallow mud and snow, and for mechanical keying to a dirt or rock surface. For very soft surfaces like deep mud and snow and soft sand, wider tires are better to keep the car floating and not digging in.
But then there's also the geometric aspect.
There is a correlation between tire width and weight. If the tire is too wide for the weight of the car, the vehicle will almost act like it is floating. Also putting a bigger tire on a lighter vehicle can cause you to have a odd tire pressure to maintain correct tire wear. The main thing to look at with tire size is the weight rating of the tires. If you put tires rated for a heavy vehicle on a small car, the car will bounce around. If you put too light weight of a tire on a heavy vehicle, the vehicle will sway and act like it has flat tires.
All the data makes me happy! Before you adjusted for weight, I was wondering if using weight per tire width units would give a more objective view, and then you did it!
Good statisticians hate the use of correlation coefficients in regression. Nor would they attempt to fit lines to data like that. If you removed the outliers the slope may even go the other way. Anyway you ended up with good conclusions. Keep different sets of tires for different uses!
I am concerned that you spread a lot of misleading information. For a test to be scientific, it MUST compare the SAME tire brand and model. Otherwise as proven by your data, your test is completely irrelevant!
FACT: Coefficient of friction does not include contact area. This is absolute scientific fact. Do wider tires get better traction? They can but for completely different reasons than most people think.
Here is how tires work: Rubber used on most tires today grip the road stronger than their ability to hold together. Try skidding your tires. If you have a soft tread, you leave rubber on the road. If you have a hard rubber tire, it leaves very little rubber on the road. In other words the tire gets better traction than its tear out strength. So, once you reach the threshold of where the rubber begins to tear off, you loose traction. Now, as the contract patch increases, you distribute the load over a greater area of the tire, which means the tire is less prone to tear out, or it takes more force to achieve tear out, as the force is distributed over a larger contact patch.
The reality is, that for the tire manufacturer, they need to pick a tire where the tear out strength vs load is maximized for a given tire width. The manufacturers tend tend to error on the side of tire tear out, as it tends to be more forgiving. The rubber stretches as it tears, and tends to not loose grip abruptly. This allows the driver to have some control, even though the tire is sliding. Harder rubber tires tend to loose grip more abruptly, making them more dangerous. In the case of a heavy truck, the weight per square inch is several times what a car tire is. This means the rubber needs to be much stronger and harder, which it dramatically increases stopping distance. It also means when it does break loose, it is very abrupt and uncontrolled.
So when you choose a tire, if you pick a softer compound, you should also switch to a wider tire. Simply going to a wider tire, may not increase traction, unless the tire is also softer, or your current tire leaves a lot of rubber on the road when you slide. Most wider tires are more likely to be sportier, and therefore are more likely to have a softer compound. Most people are going to make the right decision, but not really knowing why.
I think comparing SUV's and SUV's, Sedans vs. Sedans. trucks usually are out there on stopping distance because it is really obvious abuot the weight distribution. I hope you had a lot of fun
Friction is independent of surface area, purely wider tires do not decrease or increase stopping distance. Widening the tire allows softer and stickier rubber to be used mainly by decreasing the load on the sidewalls. Friction is determined by weight and the coefficient of friction where Friction=Coefficient of friction x Normal Force(usually the weight). You will notice that with this equation the force of friction increases linearly with the weight increase so the coefficient alone will determine the stopping distance for vehicles. The first scientist (Guillaume Amontons) to proclaim this was just about laughed out of the room until one of his peers proved him right. You can test it yourself if you have a force gauge and two building blocks tied together with a string. Do test 1 with both blocks on a table tied together, then do test 2 by stacking the second block on the first and repeat tug test (same weight half the surface area). They will take the same amount of force to move despite having the same weight and different surface areas. What really matters in a tire is what additives and rubber they are made of and how soft they are. Widening the tire reduces the load on the sidewall and decreases the rate of wear, allowing softer/"stickier" tires to be used. There you have it folks the secret to wide tires
Even though this was a very good comparison with a clear point and leaving out only information that is irrelevant for the point, I would have found it nice to include the following (especially as you will probably have a better understanding on its effects):
Heavier cars obviously have more moving mass, which increases stopping distance, but they also have more grip due to the higher force pressing down on the tires.
This could be interesting for the asphalt vs. off-road comparison, because from the data, it looks like generally, off-road traction matters a lot more than having low weight, so even though you have a heavy car that needs to lose a lot of energy to stop, the increased grip seems to have a larger impact, but on asphalt, it appears that having lower weight is a great advantage, perhaps because grip is quite good simply due to the nature of the surface.
But maybe this is also irrelevant compared to the tires themselves, I honestly don't know.
In any case, that's something I personally would have been interested in, but even though you did not include that, I still enjoyed the video very much!
There are so many factors that might influence this data I think
Every car has ABS and it might be set on different brake forces which might influence stopping distance
The ideal test would, intuitively, be a test where the wind is equal for all cars, the amount of aerodynamic drag they generate is known and taken into account, and they all apply the same total brake force for each brake (so front left has "150" (just an examplary number) force on all cars, and rear right "100"on all cars as well)
This might give beter empirical evidence.
A test where you ramp up the brake force to such a high number where all wheels would lock up might provide better insight as well
After that, a test as to how much brake force you can put in the brakes before tires lock up
I think that gives the most reliable data because I find this to appear a little too convoluted to really provide a solid answer
OK! That was really cool, not up there with a root canal, but a little dry. Now, let's do it all over again, but, let's do it in the rain.
Great job. I like it very much! Actually tire grip depends heavily on the tread temperature in the contact zone and tread destruction. Wider tires means less pressure and hence less destruction, but less heating of the contact zone. That is why there is no linear dependency between tire width and grip.
Good video Jase, good data collection. Love your work as always, but please use metric units in addition to imperial. Also, just a production note for videos of this style, gotta edit out that swallowing bro, audio doesn't all have to be one take. Keep up the good work.
The Ridge looks so fun
If load per tire is reduced when you increase surface area due to weight distribution then you need to find the balance between the cars weight and the width of the tire. You can increase tire load by adding a weight or adding aerodynamics to promote down-force which is fine if you are only concerned with braking or turning performance.
The only way to accurately make a correlation between tire width and stopping distance would require using the same vehicle under the same conditions of road surface, temperature and humidity and then vary the tire width on the vehicle using the same brand of tire as the tread pattern and tire compound will otherwise have a huge effect on the results. Even then, the aspect ratio of the tire, tire diameter and rotational inertia will play a role in the result.
Contact Patch!!! the width is only part of the equation. Disregarding the type of tire, larger side walls and tire diameter/circumference are the other parts of the equation to calculate contact patch.. After that is addressed then you can more accurately calculate PSI on the tire to the road.
What I'm getting to is that you can have 245/45/R16 vs 245/35/18 which have the same width and diameter/circumference but the 245/45/R16 will have a larger contact patch because the side walls are 4.3in vs 3.4in. Same reason you will never see low profile tires on any real track car as it destroys the contact patch.
It would have been interesting to see how the front to rear weight balance affected the distances. Theoretically, moving weight towards the rear helps with grip on acceleration with rwd vehicles, so I would think moving it forward would help with deceleration. Still a great video, I know it must have taken forever to make and I'm not trying to sound unappreciative.
Before I even watch; it depends on the surface being driven on and the tire pressure. In snow, mud, etc, more narrow tires have more weight per square inch, which helps increase traction. However, on a normal paved road, the more tire that contacts the road (wider tires) the better the grip will be, assuming the pressure is not too high..
This is an interesting analysis based upon incomplete and imperfect data. I think the process of trying to extrapolate useful information when you don't have perfect data was the most interesting part of this video. One other thing that would be interesting to look at would be the effect of tire diameter on stopping distance.
+Engineering Explained
I think instead of the contact area of the tires, you should consider the pattern of the tyres, and more importantly, the braking force/torque from the brake pad? It is the position where you slow down the car. The tyres undoubtedly affect the friction between itself and the ground, but the friction is only concerned when it comes to slip or not slip (gripping). Even the greater coefficient of friction should not be relevant to the stopping distance. How about do another test on the braking pad (although I have no idea how it can be done)?
Very nice video concerning the fundamental issues. I have been very grateful to watch your channel. I was a mechanical engineering student but I learned more from you than my professors.
Tire width is only one factor, and it has more effect on the shape of the contact patch than the size of the contact patch. Suppose you have 4000 lb vehicle with 40 psi pressure in the tires. It will have 100 sq in of contact area, or 25 sq in per tire. Supposing said vehicle has 255 section width tires (approx 10 in width) then its contact patch would be approximately 10" wide by 2.5" long. Changing tire pressure or vehicle weight will have the biggest impact on the size of this contact patch. Changing tire width or overall diameter will change the shape of the contact patch more than the size. Tire width will have a much greater impact on lateral grip than on longitudinal grip. Run at the same pressure, a wider tire on the same car is going to have a wider contact patch, but shorter longitudinal dimension to have roughly the same area of contact patch. Similarly, going to a larger overall diameter, all else being equal, will increase the contact patch in the longitudinal dimension, offering more grip for accelerating and braking, though it will also have greater rotational inertia to contend with.
When your dealing with that much mass, body control/suspension tuning should a huge factor in stopping distance.
You should have included tire height in the final table. As you know, braking force at the tire/ground interface is a torque. Taller tires should stop longer, assuming same brake sizing, since the torque of the brakes is divided by a longer torque-arm due to the large tire diameter. To sum up my point, a 255/75/17 tire will take longer to stop than a 255/50/15. Same width, different diameter.
I think a cornering test would have been more appropriate to determine if width affects grip.
12:20 this is why dual sport motorcycles have option to disable ABS for trails
but motorcyclists are complaing about some companies that make ABS disabling harder for them or automatically come back while they are offroad and cause them to lose traction during technical riding
Oh my, there are so many variables that are unaccounted for to make a strong R. Tire comp and tread pattern, not to mention size. Without comparing different widths of the same tires across the different vehicles there seems to be very little to take away.
I had 315s inside the wheel wells on custom Boyds back in the day on my 88 IROC. Cars were way lighter back then too.
Wouldn't it be better to try and compare vehicles of a certain type? If you have a heavy SUV you might have a poor weight distribution during braking while a VW Alltrack most likely has a pretty good weight distribution during braking which should give it a huge advantage.