LoL I farm and know.. mud and muddy conditions.. upgraded slightly from 17 x 265-65 to 17 x275-60 for a ford F150 (seven bolter) and it does matter as the tread available is way better and it is wider, but only a half a percent rounder.. and I am still under every speed indicator that the state has put up (just, like 1 mph on the worst). They are more expensive and no real determinable fuel mileage change. Now I come from the day where standard tires where ALL 78-80 aspect ratio and by the mid 70's 60 aspect ratio was about as good as one could get.. and of course I stuck them on my BMW 2002 and the rubbed so that took an extra rubber block to abate that problem..
you..have never been 4x4ing,,have you.this vid is sht..no one 4x4ing uses a 20'' rim..17'' is max, so you have some side wall & floatation..when let down,,plus, it depends on the ply, of any tire you use, preferably 10 ply.. your vid is bs, .35'' tires are a std 4x4 tire.. if you have ifs or cant fit 35,s. stay the fk home..i dont want to rescue you..ie prado..pos vehicle..the best tire, unless your rock crawling, is a good a/t 35'' bfg..i had dick cepek fc2, for 5 yrs, same tire, no issues, did everything.
I'm ex forestry for close to forty years. We had deep mud in Winter and lifeless dead sand in Summer. We had hundreds of vehicles. Small SUV's right up to heavy off roads 6x6 trucks, 8x8 logging machines and I drove most of them. NONE had oversize tires, none were lifted, none had winches. We drove knowing the vehicle and to the conditions. Yes, we got bogged, but it was extremely rare. We had a rule "the driver digs it out" so you'd expect absolutely no help, just an audience giving "helpful" advice. 🤣 The only "modifications" we did to some, good brand tires, heavier springs and shockers, bullbars, that was about it. My own 4x4's over the years were the same and I have driven over some of the remotest parts of Australia. Very informative video ☺
Thank you! It's really good to get a perspective from operators of diverse vehicles in the same terrain, provide some useful data. I'm guessing your vehicles didn't have ultra-wide tyres either?
@@L2SFBC I have tall and skinny road tires on a 7,000 lb/ 3175 kg/3.5t 2x4 truck. I need to recover some vehicles due to these recent California floods. If I use tire chains (4"-6" of mud), do I need to air down?
Narrow tires put more pressure on the patch and can dig/sink in mud/sand. Wide tires spread the load and can float on mud/sand. Narrow tires can get better fuel milage. (Less wind to push and less rotating mass) they also wear faster (given the same compound). However they can ride and drive better in some cases. Wide tires are heavier, can be rougher, and may not dig down when needed. Lower the pressure and they may conform around rocks and cracks better. However they are harder to roll like this. Also risks rolling a bead off. In short. Up to 6 ish inches of snow mud with a solid bottom, narrow wins. Firm road ride, Narrow wins. Conforming around and absorbing rocks at lower pressures, Wide wins. Mud with not solid bottom...Wide wins. Riding on top of harder packed snow instead of cutting down into it....Wide wins. In general all purpose off reading where you don't have the luxury or money to change tires. Wide wins. If you have lots of money to have sets of tires to choose trail conditions.... have at it. There saved you a bunch of time.
I've been saying this for years, trying to explain it to all my offroad friends. I'm so happy to see this video cause now someone with resources has proved my theory to be correct 100%!! Great topic! Great video! Great job!
All this theories means nothing compared to experience. A deflated tire works like a caterpillar track. And the soft tyre can easily ride up over the bump created by the tire itself.
The center of Australia was mapped by Len Beadel in a short wheel base landrover with standard wheels on it. He did it on his own without a winch or support vehicles. A lot of people have sat up probably at night or over a long period of time designing these off road vehicles for them to perform to their ability and to be able to manage a lot of different situations.
@@harrywalker968what is “ect”? Try etc instead, this stands for et cetera. Firstly you didn’t watch the video and secondly narrower tyres have many advantages including contact patch at certain pressures, that is fact. Your statement contains no facts as you haven’t stated in which conditions “bigger wider” is “better”.
Brilliant tutorial. I like the fuel savings, reduced road noise during travel, better snow and heavy rain traction, low carbon angle too. I learned more here in Under 30 minutes than 1.5 years of shop class and since i am one of two girls out of 26 in the class, i get a lot of guy students offering to help. Sort of a sisterly love, i return the care sort of as a nurse when they bruise & cut their fingers..
Are you for real? The extent you take measurements and analyze tires (tyres) is off the charts impressive! What a great video and I have seen a number of your videos on SUV's, road tests, you name it on your channel and they are all equally great. Thank you for all you do!
Robert really thorough as usual :) Having spent 20yrs growing rice in NSW on both black and red clay I always removed the standard 750-16 wheels/tyres from the utes and fitted at least 31-10.5's or larger. Much less damage to the tracks/paddocks and when aired down to 10psi made the difference between walking or driving home. In those conditions flotation is everything you only have to see the duals or triples on tractors.
@@timsbike4887 Tim too true, you are correct but gaining flotation on ground with no real bottom certainly helps and narrow say 750-16's definitely cut farm tracks up more than a wider tyre. Each to his own though. :)
Happy you bring this to light. In the U.S. this topic is rarely mentioned since probably the 70's. It is quite difficult to find "tall skinnies". Manufacturers don't even offer you the choice. Try finding 33x10.50r15 among manufacturers or even narrower. Good luck.
There are things you can do but it takes a little know how. And you in most cases you would have to be willing to change out the Rims to help you achieve what you are looking for. Usually - Flotation sizing is better construction for off-roading. Super Swamper 33x9.50-15 Tire also exists.
@@g.fortin3228 well you just shop around and/or buy it online. Have them ship it to the shop of your choice. The other thing you can do is to find out where that Brand of Tire(s) are sold, and then have the manager have them in stock for you if you are a regular.
Yes! The douchey truck crowd has ruined the tire market with their douchey super wide and rubber band tread. Seeing a truck with 35s but 26” wheels makes me want to throw up.
Purchasing today a set of five 255/80-17 Falken Wildpeak AT3 to replace the 285/70-17 presently clamped to the hubs of my F150. Been pondering this move for a year, now. I'm quite slow. Thank you Robert! as always for your hard work and for your always in-depth analyses on topics we find interesting and important to our veehickular lifestyles. You are, quite literally, THE MAN. Happy Holidays.
@@thedetective8150 I changed wheel offset, too, to a +25mm to bring the tread surface back to within the fender vertical (less mud splash), but just. Due to the offset change the taller tire does not rub at all when the previous wheel/tire did slightly which is another bonus. Factory wheel offset was +44mm iirc. Together the look is improved to my taste but the initial impression was underwhelming. The previous, wider tire on a 0mm offset may have looked appropriate for pavement motorsports... and while that is a look I don't mind I prefer the more conservative appearance of the truck, now. Tarmac/concrete grip is reduced for obvious reasons, then one would add the fact it's an ATIII (it's compound/durometer some have called greasy) which could be the most aggressive tread for any common All-Terrain tire. I run 36 psi Cold (D Load Range tire) and have just one recent very short (5 miles) off-highway run for which we did not air down and drove quite slowly (no greater than 15MPH) due to the exposed rock on a certain forest access road. Traction there is improved and in loose dirt. That's all I have thus far as my off-highway camper trailer/caravan is not quite finished.
@@thedetective8150 I should add that the five ATIIIs purchased are not the 255/80-17 but instead an advertised 34 X 10.50 X R17LT. They measure 33.5" X 10.6" and weigh 55 lbs each.
I've been running the thinnest tire I can get, and run a modified steel rim. It ended up being 7lbs lighter than the mag wheels it came with (3.2kg) each wheel, times 6. The performance deflated has been really impressive in sand, snow, mud, washboard, and mountain trails. I decided to go this route many years ago after a heavy snow and my 67 Micro Bus with stock (skinny) tires just sliced through the snow. But this video confirms my other experience of very competent grip when the psi is lowered, and why.
This video was surprisingly informative and well presented. My early 4x4 experience was with militsry M151 jeeps and deuce-and-a-halfs. Relatively narrow tires. Never thought much of them one way or another. I worked for a few years for an employer in the southwest coastal area that maintained a fleet of Blazers , Broncos, and Ram Chargers. OEM tires got replaced with 78- series re-tread snow tires. Handled horrible on the road and weren’t great on the beach sand either. Ironically, some flirtation with Jeep Cherokees with the police package (Goodyear Eagles) were pretty capable on the beach or on trails. Didn’t even have to lock them into 4x4 or low range. The bigger SUVs started getting fat ATs and worked better on the beach although still required 4-low to get anywhere. Suspensions make a huge difference and the Broncos worked better when fitted with Rancho systems. Even worked off road better with OEM wheels and tires. I haven’t done much of any off reading for a while, but am going to rewatch this video and do some serious homework when my Tacoma 4x4 Sport is ready for new rubber. I previously had an Expedition with a Wrangler ATs and once got stuck in my driveway in 10 inches of snow. Of further mention is that early cars such as the Ford Model Ts/As had tall narrow tires. Unless one opted for a Marmon 4x4 conversion, they were all rear wheel drive. Add tire chains in mud or snow and they’d go anywhere. Especially interesting as my late granddad’s generation learned to drive in cars from them teens, twenties,and thirties, and even while living and working in rural areas complete with muddy roads never felt the need for 4x4. Always got around fine with open rear ends and mud grips.
THANK YOU for being in my court, regarding wider vs narrower tires, even for the street! You have proven, in your contact patch analysis, what I already knew, and proclaimed on an automotive forum that I frequent, and was laughed at on there.
What kills me now days is these people putting these tires with almost no sidewall and rims sticking out beyond the pickup on their vehicles. They really are daft.
Robert, Another video that is thoroughly researched, packed with useful information, and expertly presented. You, Sir, are an expert that I trust. Keep up the good work. It is highly appreciated here. Ken Republic, Washington state USA
Love your approach to off-road performance and hiw you break it down in your videos.. Especially great for those who understand the value of math and physics and want performance over appearance.
Eye opening information. Just got my first 4x4, there's so much information out there, it makes your head spin. After watching this, I feel like I have a clear direction. You're in the minority of opinion, but I think you're right. Much of the offroading community is pushing wide tires. Oftentimes it's good not to follow the crowd. Thanks again.
@@L2SFBC You're right, because otherwise the information is just speculation and opinion. It's a letdown that there isn't more information like yours available. So, a question, is there a point of diminishing returns when it comes to tire width? Obviously tire height is restricted by clearance in your wheel arches, but is width restricted by anything? Or, is this a situation where you run as tall and as narrow as you can?
@@L2SFBC Another question, if you don't mind. Would you prioritize tire height or tire width if you had to choose? Say for example, a 235-80-17 vs 275-70-R18. Would you sacrifice the width to get the taller tire, or is width paramount, go with the 235 option?
ASPW has been a fan of narrower tyres - his conclusion is from experience, now you laid some evidence down for that. I've always thought that narrower tyres were a better bet for offroad but only theoretical hunch - Thanks for the evidence based insight!
My experience is the same; narrower better, my Defender being a case in point, and I did run wide on my Pajero. Plus, a lot of running driver training and trips. But, evidence works!!!
This was ridiculously helpful, thankyou. I have a Suzuki Grand Vitara I'm about to upgrade my wheels and tires on (from 226/65/R17 to something on a 16in wheel) and the irony of seeing a GV in this video made me smile a lot!
I always watch your videos and find them to be very informing. I'm an engineer in the trailer towing industry and love the content you've put out on towing as it makes it easy for me to teach people some of the basics on why things are they way they are, I simply send them links to your videos. I agree with most of this and was already planning to go with skinnier and taller tires on my current vehicle build. However, there are a lot of other things to consider that don't easily show up in the math. Like how in mud, icy snow, and sand the top layer can be more firm that what's below. Often once you break through that layer (especially "dry" lakebeds and iced over snow) the vehicle will sink to the frame very quickly. Having wider tires makes a very big difference because the skinny tire with a longer contact patch is putting more pressure over an area that's already had pressure from the front of the tire. The wider tire with the shorter contact patch will be covering more fresh ground and therefore be less likely to break through.
Thanks, love it when engineers comment! Yes that's a really good point I hadn't thought of. Which actually goes to the other point of reducing rolling reistance, it's the disadvantage. What I didn't get into was the distribution of pressure throughout a contact patch - it's not even, and I'm not 100% sure if it's the same for narrow/wide. I have a book on terramechanics but it doesn't say, and I can't measure it precisely. However given that the contact patches are pretty close then I doubt it'd make a massive difference.
@@L2SFBC as you mentioned many times in the video, tire dynamics are extremely complex and not fully understood yet. I actually was thinking of how pressure is distributed over the contract patch too. I'm not sure there is equipment that is easily available, but something similar to how a shoe store can find the pressure on foot with a specialized scale but for tires would be a great addition to this tire saga. Thanks for all your hard work!
I am an Engineer myself and agree with extra variables in different conditions, but I think as a general rule of thumb you can use the tall narrow tyres for general better off road performance.
I agree I've been running 11.5 in wide 33 in tires on every terrain and yes they are a little more bulky I mean they're not 35 but I get there a little more bulky. My thing is that in the Sonoran Desert with really deep what some people call Sugar Sand which does not compact at all when you drive on it like beach sand it is always extremely loose no matter what I find 11.5 wide does not make a bunch of rolling resistance the way people say do to drag it really just float right over and I can drive my old Land Rover disco that has under 200 horsepower 30 mph or more cross the softest part of the sand in hundred degree temperature of the Arizona desert and this and you can't even hardly walk through without syncing up to your ankles but when I see smaller or skinnier tires on vehicles they sink right in and can barely move. Also I think optimal contact patch also has to do with the weight of the vehicle because if something is too skinny but weighs a lot it is going to push really hard per square inch but possibly too hard and break the ground likewise if something is to light weights and the tires are too wide it can help the vehicle slide over the surface and not group very well. So I think it really depends on the terrain and the weight of the vehicle and we shouldn't just say skinny is better all the time or for certain Vehicles only it should really be based on the terrain and the weight of the vehicle. So if we determine that the 4000 lb rock crawler does really well with 11.5 wide tires then maybe 12.5 wide is better on a 5000 lb rock crawler for example
Amazing video! I have a Jeep Gladiator with Kenda Klever RT 35 x 10.5 inch tires on a 17 x 7.5 wheel and they perform amazing. So many people here in the US run wide tires. They are clueless!
What a great video and explanation. Also the additional input on the impact like the rotational weight, that is completely missing in other videos on youtube. Thank you for that content!
What a fantastic video and great explanation of tyre selection. This is the reason for the last 30 years using 4wd vehicles, I always used narrow and tall tyres. Currently I run 235/85/16 and never been happier. Wider tyres are better suited if you live places with icy and snow conditions, but you will need to upgrade your drive train to take up the extra loads.
I wouln'd be so sure about the icy and snowy part. Here in the alps there's a long going discussion among every parts of driving (so not just offroading) about which is best on snow and ice: narrow or wide, just like among the offroad comunity. And there are arguments made in every direction, and even tyre testers aren't all of the same opinion. Of yourse, if you look at iceland, where they try to float their tyres on deep snow, they have huge, almost balloon like tyres, but everybody else who doesn't do that is mixed in their opinion. Wide tyres may do better on ice, but when there is slush or powdery snow on roads, narrower tires have their advantages. The only thing relatively sure is that propper winter tyres of a reputable manufacturer outperform any AT and MT tyre on snow and ice, no matter if wider or narrower. And if you only drive on snow and ice, "nordic winter tyres" are king over "normal" winter tyres.
@@kailashkashyap3916 I personally do not recommend any tyres for both offroad and snow+ice. I strongly believe that if you have a winter season with snowy and icy conditions and freezing temperatures, it is better to use actual winter tyres (from a reputable manufacturer) during that season. And i would personally go for the narrower size. (less weight means less unsprung weight, less fuel consumption and in slush and similiar conditions more safety) And they are usually cheaper as well.
@@nirfz please at least suggest me better tyre size for off-road/mud/slush OEM size is 215/75r15 any other combination which helps me also in increasing ground clearance little bit..
Good explanation, and it is entirely consistent with my experience racing enduro motorcycles and touring off-road on adventure motorcycles. I’ve always run narrow tyres in the dirt, they drive through so much better and with the amount of really physical work required to ride a bike through sand you can actually feel a narrower tyre is significantly better. It’s interesting that pretty much all dirt bikes use 21” rims on the front, very “tall”, and most 21” tyres are relatively narrow. Unsprung weight is massively important with motorcycles too. So, intuitively I’ve carried that over to my 4WD setups, basically assuming tall and narrow is generally going to be better, and it was great to get an understanding of the science that supports this in most environments. Thanks.
Thanks, nobody has disagreed and said wide is better; but yours is one of many comments relating what is felt by personal experience to what I show in the video. I never felt my Defender on 235/85/16 lacked offroad capability even in soft sand....so I add myself to that list!
If you ever get a chance to ride a Yamaha TW, which has an obscenely wide tire, in the sand, you may change your mind. The high flotation of the balloon tires keeps you on top of the sand, making riding much easier than on skinny tires.
I am so glad you put this together Robert. I must point out one critical error in your method however. There is a vast difference in tire sizing between different manufacturers and models of tires. IE 3 265/70/17 tires of different brands will have widely varying tread widths. In addition, different tires will have drastically different behaviors on airing down. I understand that having all sizes in the same brand would be cost prohibitive. In any case, the video is great as are most that you do. Thank you.
Some excellent analysis. I've long subscribed to the "longer is better (patch!)" theory, recently putting money where mouth is, in moving from 395/85 R20 to 14R20. I'd also recommend "Defender Mods and Travels" on RUclips, with videos including "The Best Tyres for Overland Travel". Always plenty of physics based reasoning.
Informative video. One thing I’ve never seen any RUclipsr mention is the advantage of fitting the widest tyre you can on a given rim width. For example if running a 16x8 rim a 285 wide tyre can be aired down lower and have less risk of debeading than a 265 wide tyre. I use to run 285/70r17 on a 17x9 rim and use to have constant debeading issues at 20 psi. Since changed to a 285/75r16 (still 33s) on a 16x8 and have aired down as low as 10psi no issues and have never debeaded since.
Love the video and research. Did you find correlations with contact patch and vehicle weight? I would expect similar contact patch at a given pressure for different sizes because the vehicle weight did not change, and tires have a similar compliance. (Within the error shown.) 2) An advantage of large diameter tires is running lower pressure to get a larger contact patch when you want. That is helpful when the surface is not solid, like sand, gravel or loose. 3) Contact patch is different on soft surfaces like sand, mud and dirt, because of penetration where the true contact patch wraps around some of the tire. That is an advantage for wider tires because they don't sink as deep for the same contact. 4) Racing vehicles at the end of the video are purpose-built to go fast. Penetration is much less at speed, and traction demands are quite different, so be careful making tire choices for recreation off-road based on those. Finally, a choice for wide or narrow must also contemplate the terrain. A good tire choice for the desert is probably not the best tire for mud. Pluses and minuses with everything as you mention. Good job with the video.
Increased vehicle weight will increase the contact patch, yes. However...there is then more weight, and therefore more energy required to move the vehicle, and more pressure on the terrain. So it's better to have a lighter vehicle than a heavier vehicle. In circuit racing this is why aerodynamic downforce is so good - I have explained it here ruclips.net/video/P3FmufPt0Rg/видео.html - because you get the benefit of downforce but no weight. However 4x4s are too slow for any downforce. The contact patch doesn't change much unless you're talking rock when the entire tyre can rest on a sharp edge. For compression terrains it's more or less the same.
This explains why I saw no difference in sand driving with my 1979 FJ40 Landcruiser when I went from wide wheels and tires to stock wheels and tires. The stock tires improved the ride and handling. I did the change for cosmetic reasons, but was surprised at the improvement.
Indeed, an FJ40 isn't very powerful so the extra rotating mass would really have sapped power, your suspension wouldn't be designed for the extra unsprung mass, and there would be changes to the geometry of the steering. It's almost like there were a bunch of engineers who figured out the best size tyres and wheels for that car.
@@L2SFBC Your explanation of the rotating mass factor gives a good insight into why fat tires can be detrimental to performance. Also the demonstration of the contact patch being about the same - just an exchange between the same area distributed on either a transverse or longitudinal plane.
Great video. It seems that tire manufacturers should produce more narrow tire sizes than they currently do. At least in the U.S. there are few narrow sizes.
Wider tires are better for stopping. Most people here in the states don't drive off road. It's like sports cars on road courses. Wider is better. Then you can run smaller brakes.
@@2dogsmowing Narrow tires are better for gas mileage and better on snow. They more than hold their own offroad. You have to weigh the pros and cons against your preferences.
@Alan Schreiner I understand your point. I was just saying wider tires are better for stopping. It's like thinking bigger brakes help. Which they do if you're driving a race car. But if you do wider tires it does the same effect. That's all my point was.
I've modified my Astro van with 4x4 and a lift - I'm running 235/85R16 LT Falken Wildpeak AT3W's with a full size spare currently mounted under the vehicle (I had to reroute the exhaust over to the passenger side of the vehicle more to make that work) - Off road in mud, sand and over large rocks/boulders the vehicle grips and pulls through everything like a tank, especially when I'm in 4-LOW. I'm very pleased
Thanks a lot for this extremely detailed explanation. This is tyre-science at it's finest. It's always a pleasure and interesting to watch your videos. So, in general speaking, wide tires on some offroader are mostly for better looks, but not always for better performance.
They can perform better...there's never a 'never'. The main point of the video was not to assume they are always better, and make people aware of the pros and cons.
Great informative video! Just want to mention that many rock-crawlers swear by increased unsprung weight, even going so far as to put water in the tyres.
Yes, that's true..the technique is also used in radio-controlled rock crawlers and vehicles like graders and tractors. However, I'm talking here of touring-class 4X4s. I should have mentioned the rock-crawling people, you're right.
We went away from water in the tires on farm tractors in the late 1970s. Chassis weight was a far better option. Reduced air volume was detrimental to tire flex at farming speeds and loads. Friction of soil particles, lug design, tire pressure and case design all effect traction and floatation. (tractor) .
10:18 - As a Montanan this has always been my bottom line. I just don't live in areas where sand is typically a driving situation. I've long favored "pizza cutters" ;-) 7.50x16 back in the day.
I'm an off road tour guide in Southern Utah. Lots of sand! I'm interested to know if you ran these same tests at a much lower PSI. On my side by sides I run about 11 PSI. On the full size vehicles I run about 23 PSI so I can drive on pavement without issue. But, when I am going to spend significant time in the sand I'll air down to 6-8 PSI in the full size vehicles. You can see the difference in contact patch visibly with the naked eye. Awesome video!! Love stuff like this.
Nice to see someone else in the sub-10psi club with me. I have run as low as 2psi in 33's on an old CJ5 in Utah for that matter, talk about grippy, made me wonder why it was called 'slick'rock when I didnt slip haha
Great video with clear plots on graphs to illustrate your points. The relationship between tire height, width and tire pressure to contact patch may be just three of the factors to consider when choosing the tire however. Other possible factors could be: 1. What is the difference between contact pressures per square inch of narrow/wide/high prof/low prof tires? 2. What is the difference in the center of gravity between narrow/wide/high prof/low prof tires and how that affects vehicle stability? 3. What is the difference in centrifugal and centripetal forces between narrow/wide/high prof/low prof tires when stationary and when rolling at various speeds? 4. Also as you mentioned in one of the comments, what is the difference in different areas of the contact patch between narrow/wide/high prof/low prof when stationary and when rolling?
Thanks DocRocker! 1. High vs low profile - see my other video on that subject! 2. CoG - virtually nothing 3. Centripetal - low profile greater due to greater mass & further away from centre, again refer to other video 4. Rolling diameter & CP change to some degree but not significant for 4x4s, it's more a racecar thing.
A 1941 Willys Jeep is 600-650x16 and we can see that it gets out of all the obstacles of the off-road very well. The fashion is for huge tires with huge rims and elevators (and huge price). And then we complain about the death wobble ...
Thank you Thank you Thank you for this very informative video. I have been going blue in the face trying to convince people that narrow taller tyres perform better offroad. My vehicle came with 245 70 16 (29.5 inch) which i immediately changed to 245 75 16 (30.5) and now am changing to 235 85 16 (31.7 inch). Most people argue that 265 75 16 (31.6 inch) will be better but i always believed that a lighter narrower 235 85 16 tyre which is the same diameter as the 265 75 16 tyre is a better choice. Your video just reinforces that belief.
I found that the 235/85 performed well off-road, but the 265/75 was better on sealed roads, held on better especially in the wet. So, what do you drive on the most?
Firstly thanks for making the effort to do this and the information presented it was very informative. For a given diameter the length of the contact patch will determine the amount the tyre drops. Wider tyres have shorter contact patches, therefore you can air down more and still have the same wall height. So they have more in reserve, you can air down by a good few psi and still have the same wheel clearance as the narrower tyre. I bet that extra few psi will improve offroad performance way more than any differences in width. One of the best ways to improve offroad performance is to fit offroad biased tyres, but typically this has a detrimental effect on wet road handling and particularly braking. Something I value greatly as my 4WD is also my family car, having a wider tyre should help according to this video? Narrower tyres allow you to fit a bigger tyre without rubbing and mods to the car, which is a great advantage IMHO. PS all my 4WD's have been stock except for fitting a set of AT's of a size similar to stock.
Depends on use. Sometimes floatation helps, sometimes digging deep works better. The one fact you can't argue is that the more air it holds, the higher its load rating can be. So for the rear of my fullsize work trucks, a 305/70 beats a 255/85. Both are 33"
Great video, I agree with almost all of it, and I lean towards the skinny tyres. I do have dissenting views on the "myth about narrow tyres cutting through mud to hard ground" beneath (at 10.05" onward). I have driven extensively on Borneo Island, which I call home. Many of the off-road tracks we use are former logging roads. While they look like most other dirt tracks, they are actually well engineered roads able to support log-laded trucks of over 50 tonnes. These trucks operate only in dry weather and they grind the surface into a fine dust, creating a layer about 40-50mm thick. When it rains, the dust quickly becomes a slippery greasy layer. The loggers used Land Cruisers and Hilux with skinny mud tyres which DIG and clear away enough of this slick mud to then drive on firm ground exactly as wide as the tyres. The MT treads grab a handful and throws it aside with each turn. I have driven on these trails many times, in the dry and when wet. HTs and ATs fail in these conditions because the finer grooves fill up and quickly become slicks that spin helplessly. Vehicles with wide tyres struggle with stability. The self-cleaning ability of an MT is critical in these conditions. While the contact patches may be roughly the same size, the different shapes makes a difference, in the same way a sharp knife cuts and a blunt object does not. The situation is different for non-engineered dirt roads or other mud that may not have a firm bottom, so digging or cutting is not good.
Thanks for an informative post. Re the skinny tyres - why wouldn't wide ones also dig in? The tracking issue is specific to the ruts made in this situation, no?
@@L2SFBC for the same reason a sharp knife cuts best when slicing in the correct direction, along its sharp edge, and not 90 degrees to that. It is not that wider tyres can't cut at all, it is about which cuts better, a sharp blade, or a blunt one? Theory aside, I have driven along a slippery trail with my skinnies without drama while my buddy ahead was spinning circles in front of me, without steering inputs. It got so bad we aborted and turned back. I had 235/85 16s, he had 33 12.5 16s.
Just to make the comparison clearer, there were other differences in the scenario I mentioned. I was driving a long-wheel-base Defender 110, my buddy was driving a short-wheel-base LC 2, so wheelbase also has a bearing on straight-line stability. Driver experience was about the same, and track was straight so no need for steering inputs, except when trying to correct for slides. We both lowered pressures to about 25psi before tackling the stretch.
The traditional old Jeeps’ slim tyre is probably the best for most off road situations, meaning slush and mud and rocky trails and fording small streams etc. It certainly is fantastic when used in the narrow tea and coffee estate roads here in India especially in the deep slush which ensues during the rainy monsoon season. Perhaps the big fat off road tyres when they are ‘aired down’ are better for the kind of rock climbing that Jeepers and Off roaders do in places like the Moab in Arizona.
I’m actually understanding what I was taught years ago. For plow trucks especially, you want the tall lengthier tires, and to do better in softer sand or muddy conditions you’d want wider.
I just learned so much more than I was expecting when I searched this question! Also, I'm so glad I did because I was about to go wider to increase performance on my 4x4 but now have learned it's better for me to stay narrow. Thank you!
14:49 Shouldn't it be 1.6kg non-rotating = 1kg rotating? The rotating mass of 1kg is as bad as 1.6kg of non-rotating mass. Am I missing something here?
Cool video. Cheers. It would be good to have more of a control in the comparison. E.g use a bfg km3 in 305/70r16, 285/75r16, and 255/85r16. Also, it'd be great to measure the deformation over objects lateral and longitudinal to the direction of travel. I think comparing 3 different tyres of identical size would also be interesting.
Although this will be vehicle dependent here is another possible advantage: wide tires can reduce both suspension travel and steering angle due to clearance issues. On my car, changing from 33 x 12.5 R15's to 255x85R16's (both give diameter of around 33") I gained roughly 100mm/4in of suspension travel when measured on a flex ramp. I also suspect that the larger difference in contact patch you measured in the last set could well be due to differences in tire construction. It would be great to repeat the test using one brand and model of tire, but I realise it doesn't make financial sense for a small youtube channel to attempt.
Yes Peter, good points. No I can't afford all those tyres, and another problem is actually getting the tyres in exactly the sizes required, regardless of money.
crap, garbage..on what vehicle. the bigger the tire, the more weight, the more travel..& contact..i only run 35,s. nothing less..you air down a 33 your down to 30.. clearence..
Thanks Robert, this backs up my theory and discussion I had with a prominent youtuber who thinks running massive wide tyres is the only way to off road, I should have sent him the link to this video, but I doubt he'd take notice of the evidence.
@L2SFBC yes, the only evidence he presented was his opinion, I mentioned that both mining exploration and the army use narrow tyres and that they had obviously done their research. As you mentioned though, it does look good on YT 😉
A very comprehensive article and provides great food for thought. One thing that came to my mind when you were winding up and talking about the benefits of each was regarding the weight carried by the vehicle. We trundle down the road in our 4x4s ladden to the hilt on reasonably wide tyres these days. The weights are fairly constant during the whole trip. Is it right to assume that a narrow tyre has a lower carrying capacity than a larger wider tyre when considering the vehicle to be a 4x4? I specify 4x4 because we will be lowering the pressure to do some cross-country driving at some point no doubt. If we were just doing highway driving then the narrow tyres would certainly be better. But for the off-road stuff especially with a fully laden vehicle, perhaps the wider tyres still hold the top spot.
There's not really a correlation between width of tyre and load rating, so narrow is fine for load, just make sure the tyre meets or exceeds the vehicle's placard rating (see other videos where I explain this including the recent Jimny one). Look at the Defender 130, Troopy etc, both run narrow. You will find the lower-profile tyres have lower load ratings though so avoid those. The narrow tyres are lighter so there's more payload for carrying. ruclips.net/video/xyc8HYzEZPE/видео.html
One thing I find interesting is the sizes that have gone from imperial to metric with the only change being the rim diameter....31x10.5 for example are still the most common tyre size on new fourbies, though these days more common in 17-20 inch sizes than the 15s and 16s of old....
I've visited the Goodyear Technical Centre in Luxemburg and one interesting takeaway from their briefing was that style and aesthetics play a big role in final decisions. Engineers do their thing, focussing on specific performance aspects but they still have to argue with Marketing who tell them what customers want, usually based on looks. Final decision is a compromise between the two sides, plus accounting as well. So trends may not be entirely based on performance improvements, although the trend towards bigger vehicles and hence bigger brakes play a part in the move to bigger wheels.
I absolutely appreciate this but the sprung vs. unsprung weight comparison slide is reversed. 1kg rotating mass (wheel) should be equivalent to 1.6kg non-rotating mass (cargo). You have the 1.6kg of wheel weight being equal to 1kg of cargo weight. Just trying to clarify, otherwise thank you so much for putting this together and delivering it at a great pace!
I love my 255/75/17 on my Sequoia. I get better gas mileage than Toyota says I should. I've taken it down forest roads and the Lost Coast out here in California and it drove perfect
I'm Dilmar from Escola4x4 Brazil. Your channel is very good! All topics are deep explorated, with a good theory explanation and practical uses. Congratulations! I would like to use your information for my classes...
Maybe I’m mistaken, but I thought tire pressure, contact patch, and corner weight were all related (contact patch in sq in x PSI = weight on that tire). Tire carcass rigidity probably changes that, relating to your point that tires aren’t balloons. Great video and my next choice of tires will definitely be as narrow as I can reasonably fit.
Yes the three are related - the greater the normal force (weight when static, load when moving) means greater contact patch. The high the tyre pressure, the smaller the contact patch. So for heavy loads increase pressures. For greater contact patch offroad reduce pressures. Tyres are sorta kinda balloons but not exactly because of the carcass. Please share the video :-)
When it comes to adhesion and the size of the contact patch, it really shouldn’t matter for traction whether you have a lot of pressure on a small area versus a lower amount of pressure over a bigger area, except that at some point, the material of the tire itself is going to fail, which is why we get burned rubber or scratches on asphalt or rocks or other surfaces. A larger contact patch will allow more material to be in contact with the surface at the same time meaning more material would have to fail on the tire before the vehicle slips.
Theory might be complex but application for off road use is not. It's very simple. The bigger the tire, the bigger the tread, the better the performance (traction/clearance) for off-road use. The inverse is true for on road driving. The limiting factors being weight, rotational mass, fuel consumption, fuel range, cost and greater force on drive and suspension system. All those factors are a compromise depending on the driver, vehicle, terrain and budget. The best choice is always the smallest tire (in both width and height) that achieves the driver's objectives. General guidelines can be summarized for particular use and vehicle type: smaller AT tires for general off road touring; medium size tires AT for touring and medium obstacles; large MT tires for larger obstacles/difficult terrain.
Nice summary, read it twice and generally agree. Thanks. I do think the point about different offroading tyres is good. For overlanding you don't need 37s..just a waste of money and weight. Different if you're in a hardcore Jeep looking for tough tracks.
You may also wish to see why Low Profile 4x4 Tyres are Evil ruclips.net/video/xyc8HYzEZPE/видео.html
LoL I farm and know.. mud and muddy conditions.. upgraded slightly from 17 x 265-65 to 17 x275-60 for a ford F150 (seven bolter) and it does matter as the tread available is way better and it is wider, but only a half a percent rounder.. and I am still under every speed indicator that the state has put up (just, like 1 mph on the worst). They are more expensive and no real determinable fuel mileage change. Now I come from the day where standard tires where ALL 78-80 aspect ratio and by the mid 70's 60 aspect ratio was about as good as one could get.. and of course I stuck them on my BMW 2002 and the rubbed so that took an extra rubber block to abate that problem..
what...does an f1 car have to do with 4x4ing,,fk all..
you..have never been 4x4ing,,have you.this vid is sht..no one 4x4ing uses a 20'' rim..17'' is max, so you have some side wall & floatation..when let down,,plus, it depends on the ply, of any tire you use, preferably 10 ply.. your vid is bs, .35'' tires are a std 4x4 tire.. if you have ifs or cant fit 35,s. stay the fk home..i dont want to rescue you..ie prado..pos vehicle..the best tire, unless your rock crawling, is a good a/t 35'' bfg..i had dick cepek fc2, for 5 yrs, same tire, no issues, did everything.
BORING..
The Model T with it's narrow tires and wheels did a pretty good job back in the day.
"wider tires look better on your Instagram" perfectly stated. Great video, great advice.
Glad you think so!
I couldn’t stop laughing when he said that 😂
I'm ex forestry for close to forty years. We had deep mud in Winter and lifeless dead sand in Summer.
We had hundreds of vehicles. Small SUV's right up to heavy off roads 6x6 trucks, 8x8 logging machines and I drove most of them.
NONE had oversize tires, none were lifted, none had winches. We drove knowing the vehicle and to the conditions. Yes, we got bogged, but it was extremely rare. We had a rule "the driver digs it out" so you'd expect absolutely no help, just an audience giving "helpful" advice. 🤣
The only "modifications" we did to some, good brand tires, heavier springs and shockers, bullbars, that was about it.
My own 4x4's over the years were the same and I have driven over some of the remotest parts of Australia.
Very informative video ☺
Thank you! It's really good to get a perspective from operators of diverse vehicles in the same terrain, provide some useful data. I'm guessing your vehicles didn't have ultra-wide tyres either?
And that is how you fit 4 hours of university lecture material into 20 mins.
Thank you, please share :-)
Those were some very enjoyable minutes too!
@@L2SFBC
I have tall and skinny road tires on a 7,000 lb/ 3175 kg/3.5t 2x4 truck. I need to recover some vehicles due to these recent California floods. If I use tire chains (4"-6" of mud), do I need to air down?
Narrow tires put more pressure on the patch and can dig/sink in mud/sand. Wide tires spread the load and can float on mud/sand.
Narrow tires can get better fuel milage. (Less wind to push and less rotating mass) they also wear faster (given the same compound).
However they can ride and drive better in some cases.
Wide tires are heavier, can be rougher, and may not dig down when needed. Lower the pressure and they may conform around rocks and cracks better. However they are harder to roll like this. Also risks rolling a bead off.
In short. Up to 6 ish inches of snow mud with a solid bottom, narrow wins. Firm road ride, Narrow wins.
Conforming around and absorbing rocks at lower pressures, Wide wins. Mud with not solid bottom...Wide wins. Riding on top of harder packed snow instead of cutting down into it....Wide wins.
In general all purpose off reading where you don't have the luxury or money to change tires. Wide wins.
If you have lots of money to have sets of tires to choose trail conditions.... have at it.
There saved you a bunch of time.
You spelled tire wrong, lol
I've been saying this for years, trying to explain it to all my offroad friends. I'm so happy to see this video cause now someone with resources has proved my theory to be correct 100%!! Great topic! Great video! Great job!
Thank you Aaron, would appreciate a share
off roaders are all "Ego".Its big and bad..Bullshit
31x10.5R15 for life
All this theories means nothing compared to experience. A deflated tire works like a caterpillar track. And the soft tyre can easily ride up over the bump created by the tire itself.
@@Deontjie two tyres the same size can behave completely different and have different traction especially on sand.
Finally I understans why military vehicles have tall narrow tires... Thanks !!!
almost like they have engineers to figure this stuff out instead of old mates down the pub
Do they? Typical modern military vehicles have wide tires. Tires from almost a century ago are narrow, whether they are military or not.
The new military with wide tires are for heavy trucks almost not light ones
@@worldengineering7202. Exactly like the old US Army jeeps they were very lite compared to something today like a heavy hummer with armor.
The center of Australia was mapped by Len Beadel in a short wheel base landrover with standard wheels on it. He did it on his own without a winch or support vehicles. A lot of people have sat up probably at night or over a long period of time designing these off road vehicles for them to perform to their ability and to be able to manage a lot of different situations.
beadel, & others used corro, to get over dunes ect.. bigger wider tires the better..fact..
@@harrywalker968what is “ect”? Try etc instead, this stands for et cetera. Firstly you didn’t watch the video and secondly narrower tyres have many advantages including contact patch at certain pressures, that is fact. Your statement contains no facts as you haven’t stated in which conditions “bigger wider” is “better”.
Brilliant tutorial. I like the fuel savings, reduced road noise during travel, better snow and heavy rain traction, low carbon angle too. I learned more here in Under 30 minutes than 1.5 years of shop class and since i am one of two girls out of 26 in the class, i get a lot of guy students offering to help. Sort of a sisterly love, i return the care sort of as a nurse when they bruise & cut their fingers..
Thanks!
Just found this episode. Marvellous to see someone actually collecting facts on this issue. Thanks!
Are you for real? The extent you take measurements and analyze tires (tyres) is off the charts impressive! What a great video and I have seen a number of your videos on SUV's, road tests, you name it on your channel and they are all equally great. Thank you for all you do!
Glad you enjoyed it!
Best video I've seen on explaining the differences, very well produced and explained.
Robert really thorough as usual :) Having spent 20yrs growing rice in NSW on both black and red clay I always removed the standard 750-16 wheels/tyres from the utes and fitted at least 31-10.5's or larger. Much less damage to the tracks/paddocks and when aired down to 10psi made the difference between walking or driving home. In those conditions flotation is everything you only have to see the duals or triples on tractors.
On tractors though its alll about not compacting the ground. Sitting on top off to avoid ruts. Different requirement.
@@timsbike4887 Tim too true, you are correct but gaining flotation on ground with no real bottom certainly helps and narrow say 750-16's definitely cut farm tracks up more than a wider tyre. Each to his own though. :)
Happy you bring this to light. In the U.S. this topic is rarely mentioned since probably the 70's. It is quite difficult to find "tall skinnies". Manufacturers don't even offer you the choice.
Try finding 33x10.50r15 among manufacturers or even narrower. Good luck.
It's a pity there aren't many narrow options. Please share the video :-)
There are things you can do but it takes a little know how. And you in most cases you would have to be willing to change out the Rims to help you achieve what you are looking for. Usually - Flotation sizing is better construction for off-roading. Super Swamper 33x9.50-15 Tire also exists.
right on.. 33's are typically 11.5.
@@g.fortin3228 well you just shop around and/or buy it online. Have them ship it to the shop of your choice. The other thing you can do is to find out where that Brand of Tire(s) are sold, and then have the manager have them in stock for you if you are a regular.
Yes! The douchey truck crowd has ruined the tire market with their douchey super wide and rubber band tread. Seeing a truck with 35s but 26” wheels makes me want to throw up.
Purchasing today a set of five 255/80-17 Falken Wildpeak AT3 to replace the 285/70-17 presently clamped to the hubs of my F150. Been pondering this move for a year, now. I'm quite slow.
Thank you Robert! as always for your hard work and for your always in-depth analyses on topics we find interesting and important to our veehickular lifestyles. You are, quite literally, THE MAN. Happy Holidays.
Let us know how you go!
How do you like the narrow tires compared to the wider tires you had? How was road performance and looks to your vehicle?
@@thedetective8150 I changed wheel offset, too, to a +25mm to bring the tread surface back to within the fender vertical (less mud splash), but just. Due to the offset change the taller tire does not rub at all when the previous wheel/tire did slightly which is another bonus. Factory wheel offset was +44mm iirc. Together the look is improved to my taste but the initial impression was underwhelming. The previous, wider tire on a 0mm offset may have looked appropriate for pavement motorsports... and while that is a look I don't mind I prefer the more conservative appearance of the truck, now.
Tarmac/concrete grip is reduced for obvious reasons, then one would add the fact it's an ATIII (it's compound/durometer some have called greasy) which could be the most aggressive tread for any common All-Terrain tire. I run 36 psi Cold (D Load Range tire) and have just one recent very short (5 miles) off-highway run for which we did not air down and drove quite slowly (no greater than 15MPH) due to the exposed rock on a certain forest access road. Traction there is improved and in loose dirt. That's all I have thus far as my off-highway camper trailer/caravan is not quite finished.
@@thedetective8150 I should add that the five ATIIIs purchased are not the 255/80-17 but instead an advertised 34 X 10.50 X R17LT. They measure 33.5" X 10.6" and weigh 55 lbs each.
Sidewall height is also very important. It will affect ride comfort as well as how much you can deflate a tire and still drive.
Indeed!
I've been running the thinnest tire I can get, and run a modified steel rim. It ended up being 7lbs lighter than the mag wheels it came with (3.2kg) each wheel, times 6. The performance deflated has been really impressive in sand, snow, mud, washboard, and mountain trails. I decided to go this route many years ago after a heavy snow and my 67 Micro Bus with stock (skinny) tires just sliced through the snow. But this video confirms my other experience of very competent grip when the psi is lowered, and why.
Glad to hear this, thanks and appreciate the comment
This video was surprisingly informative and well presented. My early 4x4 experience was with militsry M151 jeeps and deuce-and-a-halfs. Relatively narrow tires. Never thought much of them one way or another. I worked for a few years for an employer in the southwest coastal area that maintained a fleet of Blazers , Broncos, and Ram Chargers. OEM tires got replaced with 78- series re-tread snow tires. Handled horrible on the road and weren’t great on the beach sand either. Ironically, some flirtation with Jeep Cherokees with the police package (Goodyear Eagles) were pretty capable on the beach or on trails. Didn’t even have to lock them into 4x4 or low range. The bigger SUVs started getting fat ATs and worked better on the beach although still required 4-low to get anywhere. Suspensions make a huge difference and the Broncos worked better when fitted with Rancho systems. Even worked off road better with OEM wheels and tires. I haven’t done much of any off reading for a while, but am going to rewatch this video and do some serious homework when my Tacoma 4x4 Sport is ready for new rubber. I previously had an Expedition with a Wrangler ATs and once got stuck in my driveway in 10 inches of snow. Of further mention is that early cars such as the Ford Model Ts/As had tall narrow tires. Unless one opted for a Marmon 4x4 conversion, they were all rear wheel drive. Add tire chains in mud or snow and they’d go anywhere. Especially interesting as my late granddad’s generation learned to drive in cars from them teens, twenties,and thirties, and even while living and working in rural areas complete with muddy roads never felt the need for 4x4. Always got around fine with open rear ends and mud grips.
THANK YOU for being in my court, regarding wider vs narrower tires, even for the street! You have proven, in your contact patch analysis, what I already knew, and proclaimed on an automotive forum that I frequent, and was laughed at on there.
Hah thanks I have the same problem! Please share far and wide...let the naysayers bring their data!
What kills me now days is these people putting these tires with almost no sidewall and rims sticking out beyond the pickup on their vehicles. They really are daft.
Robert, Another video that is thoroughly researched, packed with useful information, and expertly presented. You, Sir, are an expert that I trust. Keep up the good work. It is highly appreciated here. Ken Republic, Washington state USA
Love your approach to off-road performance and hiw you break it down in your videos.. Especially great for those who understand the value of math and physics and want performance over appearance.
I appreciate that, thank you!
Thank you for doing the research and posting this video!
It certainly makes it clear.
Narrow and high makes sense to for off roading ! Thanks for explaining !
thank you for your hardwork. this is one of the most underated 4x4 chanel
Thank you, please share!
Eye opening information. Just got my first 4x4, there's so much information out there, it makes your head spin. After watching this, I feel like I have a clear direction. You're in the minority of opinion, but I think you're right. Much of the offroading community is pushing wide tires. Oftentimes it's good not to follow the crowd. Thanks again.
Ask people three questions.
1. Why
2. How
3. Where is the proof and data?
Mostly it's all I heard this I know that.
@@L2SFBC You're right, because otherwise the information is just speculation and opinion. It's a letdown that there isn't more information like yours available. So, a question, is there a point of diminishing returns when it comes to tire width? Obviously tire height is restricted by clearance in your wheel arches, but is width restricted by anything? Or, is this a situation where you run as tall and as narrow as you can?
Yes there is but I doubt you'd find a tyre that reaches that limit.
@@L2SFBC Another question, if you don't mind. Would you prioritize tire height or tire width if you had to choose? Say for example, a 235-80-17 vs 275-70-R18. Would you sacrifice the width to get the taller tire, or is width paramount, go with the 235 option?
@artvandelay1099 tall
ASPW has been a fan of narrower tyres - his conclusion is from experience, now you laid some evidence down for that. I've always thought that narrower tyres were a better bet for offroad but only theoretical hunch - Thanks for the evidence based insight!
My experience is the same; narrower better, my Defender being a case in point, and I did run wide on my Pajero. Plus, a lot of running driver training and trips. But, evidence works!!!
This was ridiculously helpful, thankyou. I have a Suzuki Grand Vitara I'm about to upgrade my wheels and tires on (from 226/65/R17 to something on a 16in wheel) and the irony of seeing a GV in this video made me smile a lot!
I always watch your videos and find them to be very informing. I'm an engineer in the trailer towing industry and love the content you've put out on towing as it makes it easy for me to teach people some of the basics on why things are they way they are, I simply send them links to your videos.
I agree with most of this and was already planning to go with skinnier and taller tires on my current vehicle build. However, there are a lot of other things to consider that don't easily show up in the math. Like how in mud, icy snow, and sand the top layer can be more firm that what's below. Often once you break through that layer (especially "dry" lakebeds and iced over snow) the vehicle will sink to the frame very quickly. Having wider tires makes a very big difference because the skinny tire with a longer contact patch is putting more pressure over an area that's already had pressure from the front of the tire. The wider tire with the shorter contact patch will be covering more fresh ground and therefore be less likely to break through.
Thanks, love it when engineers comment! Yes that's a really good point I hadn't thought of. Which actually goes to the other point of reducing rolling reistance, it's the disadvantage. What I didn't get into was the distribution of pressure throughout a contact patch - it's not even, and I'm not 100% sure if it's the same for narrow/wide. I have a book on terramechanics but it doesn't say, and I can't measure it precisely. However given that the contact patches are pretty close then I doubt it'd make a massive difference.
@@L2SFBC as you mentioned many times in the video, tire dynamics are extremely complex and not fully understood yet. I actually was thinking of how pressure is distributed over the contract patch too. I'm not sure there is equipment that is easily available, but something similar to how a shoe store can find the pressure on foot with a specialized scale but for tires would be a great addition to this tire saga. Thanks for all your hard work!
I am an Engineer myself and agree with extra variables in different conditions, but I think as a general rule of thumb you can use the tall narrow tyres for general better off road performance.
Incredibly insightful. Agree completely
I agree I've been running 11.5 in wide 33 in tires on every terrain and yes they are a little more bulky I mean they're not 35 but I get there a little more bulky. My thing is that in the Sonoran Desert with really deep what some people call Sugar Sand which does not compact at all when you drive on it like beach sand it is always extremely loose no matter what I find 11.5 wide does not make a bunch of rolling resistance the way people say do to drag it really just float right over and I can drive my old Land Rover disco that has under 200 horsepower 30 mph or more cross the softest part of the sand in hundred degree temperature of the Arizona desert and this and you can't even hardly walk through without syncing up to your ankles but when I see smaller or skinnier tires on vehicles they sink right in and can barely move. Also I think optimal contact patch also has to do with the weight of the vehicle because if something is too skinny but weighs a lot it is going to push really hard per square inch but possibly too hard and break the ground likewise if something is to light weights and the tires are too wide it can help the vehicle slide over the surface and not group very well. So I think it really depends on the terrain and the weight of the vehicle and we shouldn't just say skinny is better all the time or for certain Vehicles only it should really be based on the terrain and the weight of the vehicle. So if we determine that the 4000 lb rock crawler does really well with 11.5 wide tires then maybe 12.5 wide is better on a 5000 lb rock crawler for example
Excellent information and well presented. That painted tire/paper idea was brilliant. Thank you.
Amazing video! I have a Jeep Gladiator with Kenda Klever RT 35 x 10.5 inch tires on a 17 x 7.5 wheel and they perform amazing. So many people here in the US run wide tires. They are clueless!
What a great video and explanation. Also the additional input on the impact like the rotational weight, that is completely missing in other videos on youtube. Thank you for that content!
Glad it was helpful! Please share :-)
What a fantastic video and great explanation of tyre selection.
This is the reason for the last 30 years using 4wd vehicles, I always used narrow and tall tyres.
Currently I run 235/85/16 and never been happier.
Wider tyres are better suited if you live places with icy and snow conditions, but you will need to upgrade your drive train to take up the extra loads.
Ah yes I ran 235 86 16 on my TD5 Defender. It's almost like the engineers had a clue what they were doing!
I wouln'd be so sure about the icy and snowy part. Here in the alps there's a long going discussion among every parts of driving (so not just offroading) about which is best on snow and ice: narrow or wide, just like among the offroad comunity. And there are arguments made in every direction, and even tyre testers aren't all of the same opinion.
Of yourse, if you look at iceland, where they try to float their tyres on deep snow, they have huge, almost balloon like tyres, but everybody else who doesn't do that is mixed in their opinion.
Wide tyres may do better on ice, but when there is slush or powdery snow on roads, narrower tires have their advantages.
The only thing relatively sure is that propper winter tyres of a reputable manufacturer outperform any AT and MT tyre on snow and ice, no matter if wider or narrower. And if you only drive on snow and ice, "nordic winter tyres" are king over "normal" winter tyres.
@@nirfzmy current tyre size is 215/75r15 should I go for 235/75r15 or do you suggest any for off-road+ snow/ice
@@kailashkashyap3916 I personally do not recommend any tyres for both offroad and snow+ice. I strongly believe that if you have a winter season with snowy and icy conditions and freezing temperatures, it is better to use actual winter tyres (from a reputable manufacturer) during that season.
And i would personally go for the narrower size. (less weight means less unsprung weight, less fuel consumption and in slush and similiar conditions more safety)
And they are usually cheaper as well.
@@nirfz please at least suggest me better tyre size for off-road/mud/slush OEM size is 215/75r15 any other combination which helps me also in increasing ground clearance little bit..
Watched this again a second time. Excellent. Thank you Dr Pepper.
I learnt this from Robert Peppers’ book a few years ago now. Highly recommend.
Good explanation, and it is entirely consistent with my experience racing enduro motorcycles and touring off-road on adventure motorcycles. I’ve always run narrow tyres in the dirt, they drive through so much better and with the amount of really physical work required to ride a bike through sand you can actually feel a narrower tyre is significantly better. It’s interesting that pretty much all dirt bikes use 21” rims on the front, very “tall”, and most 21” tyres are relatively narrow. Unsprung weight is massively important with motorcycles too. So, intuitively I’ve carried that over to my 4WD setups, basically assuming tall and narrow is generally going to be better, and it was great to get an understanding of the science that supports this in most environments. Thanks.
Thanks, nobody has disagreed and said wide is better; but yours is one of many comments relating what is felt by personal experience to what I show in the video. I never felt my Defender on 235/85/16 lacked offroad capability even in soft sand....so I add myself to that list!
If you ever get a chance to ride a Yamaha TW, which has an obscenely wide tire, in the sand, you may change your mind. The high flotation of the balloon tires keeps you on top of the sand, making riding much easier than on skinny tires.
Excellent presentation a total eye opener you've convinced me. I'll be passing this along to other Overlanders.
Thanks for all of that. I had no idea there was so much involved and I am grateful that someone put so much effort into explaining it so well.
You're welcome!
I've run Dunlop 7.50R/16 on my old landrover and my Troopy for 36 yrs, never had a problem off road or on.
10:29 This is an excellent point that I'm shocked I've never heard anyone else mention before!
+1 .. Great informative RUclips site Herr Robert Pepper. .. Subscribed. .. Cheers, Vail, Colorado
Thank you Michael
I am so glad you put this together Robert. I must point out one critical error in your method however. There is a vast difference in tire sizing between different manufacturers and models of tires. IE 3 265/70/17 tires of different brands will have widely varying tread widths. In addition, different tires will have drastically different behaviors on airing down. I understand that having all sizes in the same brand would be cost prohibitive. In any case, the video is great as are most that you do. Thank you.
This is the exact reason I stick to OEM size aggressive tire, thank you for your insight.
Some excellent analysis. I've long subscribed to the "longer is better (patch!)" theory, recently putting money where mouth is, in moving from 395/85 R20 to 14R20. I'd also recommend "Defender Mods and Travels" on RUclips, with videos including "The Best Tyres for Overland Travel". Always plenty of physics based reasoning.
Absolut lecture about tires contact patch. I believe I knew this, but now I understand why. Thank you Robert, great work
Thanks for watching!
@@L2SFBC Im a suscriben now 👍🏻
Informative video.
One thing I’ve never seen any RUclipsr mention is the advantage of fitting the widest tyre you can on a given rim width.
For example if running a 16x8 rim a 285 wide tyre can be aired down lower and have less risk of debeading than a 265 wide tyre.
I use to run 285/70r17 on a 17x9 rim and use to have constant debeading issues at 20 psi.
Since changed to a 285/75r16 (still 33s) on a 16x8 and have aired down as low as 10psi no issues and have never debeaded since.
Love the video and research. Did you find correlations with contact patch and vehicle weight? I would expect similar contact patch at a given pressure for different sizes because the vehicle weight did not change, and tires have a similar compliance. (Within the error shown.)
2) An advantage of large diameter tires is running lower pressure to get a larger contact patch when you want. That is helpful when the surface is not solid, like sand, gravel or loose.
3) Contact patch is different on soft surfaces like sand, mud and dirt, because of penetration where the true contact patch wraps around some of the tire. That is an advantage for wider tires because they don't sink as deep for the same contact.
4) Racing vehicles at the end of the video are purpose-built to go fast. Penetration is much less at speed, and traction demands are quite different, so be careful making tire choices for recreation off-road based on those.
Finally, a choice for wide or narrow must also contemplate the terrain. A good tire choice for the desert is probably not the best tire for mud.
Pluses and minuses with everything as you mention. Good job with the video.
Increased vehicle weight will increase the contact patch, yes. However...there is then more weight, and therefore more energy required to move the vehicle, and more pressure on the terrain. So it's better to have a lighter vehicle than a heavier vehicle. In circuit racing this is why aerodynamic downforce is so good - I have explained it here ruclips.net/video/P3FmufPt0Rg/видео.html - because you get the benefit of downforce but no weight. However 4x4s are too slow for any downforce.
The contact patch doesn't change much unless you're talking rock when the entire tyre can rest on a sharp edge. For compression terrains it's more or less the same.
Good video. Educational
We have mostly mud and the best tire is the discontinued
Co-op grip spur 7.50.16
This explains why I saw no difference in sand driving with my 1979 FJ40 Landcruiser when I went from wide wheels and tires to stock wheels and tires. The stock tires improved the ride and handling. I did the change for cosmetic reasons, but was surprised at the improvement.
Indeed, an FJ40 isn't very powerful so the extra rotating mass would really have sapped power, your suspension wouldn't be designed for the extra unsprung mass, and there would be changes to the geometry of the steering.
It's almost like there were a bunch of engineers who figured out the best size tyres and wheels for that car.
@@L2SFBC Your explanation of the rotating mass factor gives a good insight into why fat tires can be detrimental to performance. Also the demonstration of the contact patch being about the same - just an exchange between the same area distributed on either a transverse or longitudinal plane.
Thank you again for parting with some of your knowledge Robert. Cheers
Very welcome, please share!
Great video. It seems that tire manufacturers should produce more narrow tire sizes than they currently do. At least in the U.S. there are few narrow sizes.
Totally agree. Please share :-)
unfortunately it seems like a trend that's hard to reverse. BFGoodrich seem to be holding on to some "legacy specs"
Wider tires are better for stopping. Most people here in the states don't drive off road.
It's like sports cars on road courses. Wider is better. Then you can run smaller brakes.
@@2dogsmowing Narrow tires are better for gas mileage and better on snow. They more than hold their own offroad. You have to weigh the pros and cons against your preferences.
@Alan Schreiner I understand your point. I was just saying wider tires are better for stopping. It's like thinking bigger brakes help. Which they do if you're driving a race car. But if you do wider tires it does the same effect.
That's all my point was.
I've modified my Astro van with 4x4 and a lift - I'm running 235/85R16 LT Falken Wildpeak AT3W's with a full size spare currently mounted under the vehicle (I had to reroute the exhaust over to the passenger side of the vehicle more to make that work) - Off road in mud, sand and over large rocks/boulders the vehicle grips and pulls through everything like a tank, especially when I'm in 4-LOW. I'm very pleased
Good to know - what's an Astro Van?
Thanks a lot for this extremely detailed explanation. This is tyre-science at it's finest. It's always a pleasure and interesting to watch your videos. So, in general speaking, wide tires on some offroader are mostly for better looks, but not always for better performance.
They can perform better...there's never a 'never'. The main point of the video was not to assume they are always better, and make people aware of the pros and cons.
Great informative video! Just want to mention that many rock-crawlers swear by increased unsprung weight, even going so far as to put water in the tyres.
Yes, that's true..the technique is also used in radio-controlled rock crawlers and vehicles like graders and tractors. However, I'm talking here of touring-class 4X4s. I should have mentioned the rock-crawling people, you're right.
@@L2SFBC Is the additional unsprung weight in rockcrawlers for traction or lowering the CG or a combination of both?
@@iffykidmn8170combination of both
We went away from water in the tires on farm tractors in the late 1970s. Chassis weight was a far better option. Reduced air volume was detrimental to tire flex at farming speeds and loads. Friction of soil particles, lug design, tire pressure and case design all effect traction and floatation. (tractor) .
10:18 - As a Montanan this has always been my bottom line. I just don't live in areas where sand is typically a driving situation. I've long favored "pizza cutters" ;-) 7.50x16 back in the day.
Looks like I’m going 255s on my Tacoma 2023 sr5 4x4 thanks ALOT for getting me outa the rabbit hole. Whew
You bet!
Yeah I understand cause a lot of times it's not just rabbits in the rabbit hole and I sure hate it when that happens!
I'm an off road tour guide in Southern Utah. Lots of sand! I'm interested to know if you ran these same tests at a much lower PSI. On my side by sides I run about 11 PSI. On the full size vehicles I run about 23 PSI so I can drive on pavement without issue. But, when I am going to spend significant time in the sand I'll air down to 6-8 PSI in the full size vehicles. You can see the difference in contact patch visibly with the naked eye. Awesome video!! Love stuff like this.
Fantastic, thanks Mike! I've done one on tyre pressures in sand, down to 10psi ruclips.net/video/uN0Tf2eYPE8/видео.html
Nice to see someone else in the sub-10psi club with me. I have run as low as 2psi in 33's on an old CJ5 in Utah for that matter, talk about grippy, made me wonder why it was called 'slick'rock when I didnt slip haha
Always nice to see the research behind the conclusions.
It makes sense.
Thank you, please share :-)
Thank you! I have been looking for a proven and scientific comparison such as this one. Keep up the good work.
Watched this during work. Made me feel productive
I'm almost afraid to ask what you do at work?
Brilliant research mate, thank you!
Great video with clear plots on graphs to illustrate your points.
The relationship between tire height, width and tire pressure to contact patch may be just three of the factors to consider when choosing the tire however.
Other possible factors could be:
1. What is the difference between contact pressures per square inch of narrow/wide/high prof/low prof tires?
2. What is the difference in the center of gravity between narrow/wide/high prof/low prof tires and how that affects vehicle stability?
3. What is the difference in centrifugal and centripetal forces between narrow/wide/high prof/low prof tires when stationary and when rolling at various speeds?
4. Also as you mentioned in one of the comments, what is the difference in different areas of the contact patch between narrow/wide/high prof/low prof when stationary and when rolling?
Thanks DocRocker!
1. High vs low profile - see my other video on that subject!
2. CoG - virtually nothing
3. Centripetal - low profile greater due to greater mass & further away from centre, again refer to other video
4. Rolling diameter & CP change to some degree but not significant for 4x4s, it's more a racecar thing.
👏🏼👏🏼
Fantastic research job!! And super good info condensation to make a video of just 18min to explain it.
Great
Glad you liked it! Please share :-)
Your analysis & data is extremely helpful. Thank you.
You're very welcome!
YOU are FANTASTIC.
YOU are GREAT.
THANK YOU Robert. Thank You.
Thanks Terry :-)
A 1941 Willys Jeep is 600-650x16 and we can see that it gets out of all the obstacles of the off-road very well. The fashion is for huge tires with huge rims and elevators (and huge price). And then we complain about the death wobble ...
This is so good, that very much for your hard work Robert!
My pleasure!
Thanks for that...have been in a crossroads of 305/70/17 or 285/75/17 = 33.8, the 305 meant to be wider and 285 taller. This vid helped!
Another tour de force Rober!
Thank you Thank you Thank you for this very informative video. I have been going blue in the face trying to convince people that narrow taller tyres perform better offroad.
My vehicle came with 245 70 16 (29.5 inch) which i immediately changed to 245 75 16 (30.5) and now am changing to 235 85 16 (31.7 inch). Most people argue that 265 75 16 (31.6 inch) will be better but i always believed that a lighter narrower 235 85 16 tyre which is the same diameter as the 265 75 16 tyre is a better choice.
Your video just reinforces that belief.
Pleased to have helped, would appreciate a share! The 235/85/16 is a great tyre, ran them on my Defender for years.
I found that the 235/85 performed well off-road, but the 265/75 was better on sealed roads, held on better especially in the wet. So, what do you drive on the most?
What a fantastic, thorough video!
Thanks DKV
Firstly thanks for making the effort to do this and the information presented it was very informative.
For a given diameter the length of the contact patch will determine the amount the tyre drops. Wider tyres have shorter contact patches, therefore you can air down more and still have the same wall height. So they have more in reserve, you can air down by a good few psi and still have the same wheel clearance as the narrower tyre. I bet that extra few psi will improve offroad performance way more than any differences in width.
One of the best ways to improve offroad performance is to fit offroad biased tyres, but typically this has a detrimental effect on wet road handling and particularly braking. Something I value greatly as my 4WD is also my family car, having a wider tyre should help according to this video?
Narrower tyres allow you to fit a bigger tyre without rubbing and mods to the car, which is a great advantage IMHO.
PS all my 4WD's have been stock except for fitting a set of AT's of a size similar to stock.
Depends on use. Sometimes floatation helps, sometimes digging deep works better. The one fact you can't argue is that the more air it holds, the higher its load rating can be. So for the rear of my fullsize work trucks, a 305/70 beats a 255/85. Both are 33"
Why does a wide tire have more flotation if the contact patch is virtually the same?
Thanks for sharing, it is the most comprehensive video I saw
Glad it was helpful! Please share :-)
Great video, I agree with almost all of it, and I lean towards the skinny tyres. I do have dissenting views on the "myth about narrow tyres cutting through mud to hard ground" beneath (at 10.05" onward). I have driven extensively on Borneo Island, which I call home. Many of the off-road tracks we use are former logging roads. While they look like most other dirt tracks, they are actually well engineered roads able to support log-laded trucks of over 50 tonnes. These trucks operate only in dry weather and they grind the surface into a fine dust, creating a layer about 40-50mm thick. When it rains, the dust quickly becomes a slippery greasy layer. The loggers used Land Cruisers and Hilux with skinny mud tyres which DIG and clear away enough of this slick mud to then drive on firm ground exactly as wide as the tyres. The MT treads grab a handful and throws it aside with each turn. I have driven on these trails many times, in the dry and when wet. HTs and ATs fail in these conditions because the finer grooves fill up and quickly become slicks that spin helplessly. Vehicles with wide tyres struggle with stability. The self-cleaning ability of an MT is critical in these conditions. While the contact patches may be roughly the same size, the different shapes makes a difference, in the same way a sharp knife cuts and a blunt object does not. The situation is different for non-engineered dirt roads or other mud that may not have a firm bottom, so digging or cutting is not good.
Thanks for an informative post. Re the skinny tyres - why wouldn't wide ones also dig in? The tracking issue is specific to the ruts made in this situation, no?
@@L2SFBC for the same reason a sharp knife cuts best when slicing in the correct direction, along its sharp edge, and not 90 degrees to that. It is not that wider tyres can't cut at all, it is about which cuts better, a sharp blade, or a blunt one? Theory aside, I have driven along a slippery trail with my skinnies without drama while my buddy ahead was spinning circles in front of me, without steering inputs. It got so bad we aborted and turned back. I had 235/85 16s, he had 33 12.5 16s.
Just to make the comparison clearer, there were other differences in the scenario I mentioned. I was driving a long-wheel-base Defender 110, my buddy was driving a short-wheel-base LC 2, so wheelbase also has a bearing on straight-line stability. Driver experience was about the same, and track was straight so no need for steering inputs, except when trying to correct for slides. We both lowered pressures to about 25psi before tackling the stretch.
The traditional old Jeeps’ slim tyre is probably the best for most off road situations, meaning slush and mud and rocky trails and fording small streams etc. It certainly is fantastic when used in the narrow tea and coffee estate roads here in India especially in the deep slush which ensues during the rainy monsoon season.
Perhaps the big fat off road tyres when they are ‘aired down’ are better for the kind of rock climbing that Jeepers and Off roaders do in places like the Moab in Arizona.
Absolutely there is no "always best". The point of the video is that wide isn't always best.
Wow, it takes a lot to impress me, but . . . you covered basically everything I could think of congrats; VERY good video!
Wow, thanks! Please share the video :-)
I’m actually understanding what I was taught years ago. For plow trucks especially, you want the tall lengthier tires, and to do better in softer sand or muddy conditions you’d want wider.
Excellent engineering analysis
Thanks so much!
I couldn't agree more. Great video.
I just learned so much more than I was expecting when I searched this question! Also, I'm so glad I did because I was about to go wider to increase performance on my 4x4 but now have learned it's better for me to stay narrow. Thank you!
Glad to help, please share!
put some 295/50 r15 on my cj7, never got stuck, good for street, sand, muddy fields, pulled people out with them.
14:49 Shouldn't it be 1.6kg non-rotating = 1kg rotating? The rotating mass of 1kg is as bad as 1.6kg of non-rotating mass. Am I missing something here?
You are correct
As an engineer I really appreciate this video. Great video!
Thank you very much! Please share :-)
Very detailed research and excellent explanation. Thank you.
Cool video. Cheers. It would be good to have more of a control in the comparison. E.g use a bfg km3 in 305/70r16, 285/75r16, and 255/85r16.
Also, it'd be great to measure the deformation over objects lateral and longitudinal to the direction of travel.
I think comparing 3 different tyres of identical size would also be interesting.
Although this will be vehicle dependent here is another possible advantage: wide tires can reduce both suspension travel and steering angle due to clearance issues. On my car, changing from 33 x 12.5 R15's to 255x85R16's (both give diameter of around 33") I gained roughly 100mm/4in of suspension travel when measured on a flex ramp.
I also suspect that the larger difference in contact patch you measured in the last set could well be due to differences in tire construction. It would be great to repeat the test using one brand and model of tire, but I realise it doesn't make financial sense for a small youtube channel to attempt.
Yes Peter, good points. No I can't afford all those tyres, and another problem is actually getting the tyres in exactly the sizes required, regardless of money.
crap, garbage..on what vehicle. the bigger the tire, the more weight, the more travel..& contact..i only run 35,s. nothing less..you air down a 33 your down to 30.. clearence..
@@harrywalker968 the wider tires rub on the inside of the wheel arches at the rear and the spring perches at the front. Nothing to do with weight.
For real enthusiast who install extremely huge tyre, they will certainly install suspension LIFT and Wheel spacer.
@@er.m.s8930 "Real" enthusiasts don't use wheel spacers.
Awesome video! Very comprehensive, please do more!
Thanks, will do! Please share :-)
Thanks Robert, this backs up my theory and discussion I had with a prominent youtuber who thinks running massive wide tyres is the only way to off road, I should have sent him the link to this video, but I doubt he'd take notice of the evidence.
Send it anyway! Always happy to hear differing points of view, but preferably with evidence.
@L2SFBC yes, the only evidence he presented was his opinion, I mentioned that both mining exploration and the army use narrow tyres and that they had obviously done their research. As you mentioned though, it does look good on YT 😉
Also see recent comment from Otto the foresty guy.
A very comprehensive article and provides great food for thought. One thing that came to my mind when you were winding up and talking about the benefits of each was regarding the weight carried by the vehicle. We trundle down the road in our 4x4s ladden to the hilt on reasonably wide tyres these days. The weights are fairly constant during the whole trip. Is it right to assume that a narrow tyre has a lower carrying capacity than a larger wider tyre when considering the vehicle to be a 4x4? I specify 4x4 because we will be lowering the pressure to do some cross-country driving at some point no doubt. If we were just doing highway driving then the narrow tyres would certainly be better. But for the off-road stuff especially with a fully laden vehicle, perhaps the wider tyres still hold the top spot.
There's not really a correlation between width of tyre and load rating, so narrow is fine for load, just make sure the tyre meets or exceeds the vehicle's placard rating (see other videos where I explain this including the recent Jimny one). Look at the Defender 130, Troopy etc, both run narrow. You will find the lower-profile tyres have lower load ratings though so avoid those. The narrow tyres are lighter so there's more payload for carrying. ruclips.net/video/xyc8HYzEZPE/видео.html
Putting narrow tires on my truck this week. From the sound of it I'm going to do just fine 👌🏼
Sounds great!
Great content. Respect from India
Good info. I run a 255/80R17 on my Pajero/Montero which is not the norm in the US but I prefer it.
One thing I find interesting is the sizes that have gone from imperial to metric with the only change being the rim diameter....31x10.5 for example are still the most common tyre size on new fourbies, though these days more common in 17-20 inch sizes than the 15s and 16s of old....
I've visited the Goodyear Technical Centre in Luxemburg and one interesting takeaway from their briefing was that style and aesthetics play a big role in final decisions. Engineers do their thing, focussing on specific performance aspects but they still have to argue with Marketing who tell them what customers want, usually based on looks. Final decision is a compromise between the two sides, plus accounting as well. So trends may not be entirely based on performance improvements, although the trend towards bigger vehicles and hence bigger brakes play a part in the move to bigger wheels.
Yes I have interviewed an exec and he said the same. Sad really.
I absolutely appreciate this but the sprung vs. unsprung weight comparison slide is reversed. 1kg rotating mass (wheel) should be equivalent to 1.6kg non-rotating mass (cargo).
You have the 1.6kg of wheel weight being equal to 1kg of cargo weight.
Just trying to clarify, otherwise thank you so much for putting this together and delivering it at a great pace!
Farm tractors here in SoCal use skinny tires to track in super thick mud with ease.
And all around the world!
I love my 255/75/17 on my Sequoia. I get better gas mileage than Toyota says I should. I've taken it down forest roads and the Lost Coast out here in California and it drove perfect
Very interesting. You put a very credible case for you conclusions.
Graham
I never like to make claims without an explanation and evidence!
I'm Dilmar from Escola4x4 Brazil. Your channel is very good! All topics are deep explorated, with a good theory explanation and practical uses. Congratulations! I would like to use your information for my classes...
Hi Dilmar, always open to collaborating with people. Contact me via l2sfbc.com and let's talk.
@@L2SFBC done
Maybe I’m mistaken, but I thought tire pressure, contact patch, and corner weight were all related (contact patch in sq in x PSI = weight on that tire). Tire carcass rigidity probably changes that, relating to your point that tires aren’t balloons.
Great video and my next choice of tires will definitely be as narrow as I can reasonably fit.
Yes the three are related - the greater the normal force (weight when static, load when moving) means greater contact patch. The high the tyre pressure, the smaller the contact patch. So for heavy loads increase pressures. For greater contact patch offroad reduce pressures. Tyres are sorta kinda balloons but not exactly because of the carcass. Please share the video :-)
When it comes to adhesion and the size of the contact patch, it really shouldn’t matter for traction whether you have a lot of pressure on a small area versus a lower amount of pressure over a bigger area, except that at some point, the material of the tire itself is going to fail, which is why we get burned rubber or scratches on asphalt or rocks or other surfaces. A larger contact patch will allow more material to be in contact with the surface at the same time meaning more material would have to fail on the tire before the vehicle slips.
Yes, that large/small high/low pressure thing is what physics equations say...but the reality is different.
Theory might be complex but application for off road use is not. It's very simple. The bigger the tire, the bigger the tread, the better the performance (traction/clearance) for off-road use. The inverse is true for on road driving. The limiting factors being weight, rotational mass, fuel consumption, fuel range, cost and greater force on drive and suspension system. All those factors are a compromise depending on the driver, vehicle, terrain and budget. The best choice is always the smallest tire (in both width and height) that achieves the driver's objectives.
General guidelines can be summarized for particular use and vehicle type: smaller AT tires for general off road touring; medium size tires AT for touring and medium obstacles; large MT tires for larger obstacles/difficult terrain.
Nice summary, read it twice and generally agree. Thanks. I do think the point about different offroading tyres is good. For overlanding you don't need 37s..just a waste of money and weight. Different if you're in a hardcore Jeep looking for tough tracks.
I live in Utah. Home off offroading. We like are tires big and wide. Rock crawler stuff.