Depending on the year of your RT the TPMS display is temperature compensated (see a somewhat confusing description in the manual). So a compensated reading of 37 degrees does not directly equate to a gauge reading...unless the ambient temperature is the same as the bike uses for that measurement. Ex: If the ambient air temp is 50 when the tire is filled to 36lbs...the TPMS will read a higher pressure. It would be interesting to take those gauges to a shop that has a calibrated gauge and test against that. That will be a good indicator of the comparison stability. There are NIST certifications for gauges but that's usually overkill for tire gauge. However buying a gauge that conforms to ANSI B40.1 is a good bet
Yes, that's right. But, the temperature compensation really comes into play in more extreme temps. I purposely ran this test in a heated garage where it was in the low 60s F. Maybe not perfectly aligned with the sensor, but pretty close. A tire running on the highway in summer temps can easily go north of 100 degrees F. Really the takeaway for me is not to put too much trust in any one gauge or sensor and to check them against each other once in a while. We'll never get perfect accuracy in consumer grade gauges.
Great video. I would say there is a difference between Accuracy and Precision. Outliers that are still precise even though not accurate, may continue to be used. Just write the calibration on it with a sharpy, Example Slime gauge -5, means it reads 5 degrees lower than actual. Another test that would be interesting for those of you that live in areas with large temperature changes is testing these gauges inside at 20C/70F vs. outside at -10C/20F, to see how it affect reading, using cars that are acclimatised to their environments (not moving an inside car out for example)
Great comparison. I only rely on the TPMS on my 2014 R1200RT while riding and use a digital when at home for a more accurate check. I carry a battery powered air pump that has been accurate and handy if I or fellow rider needs air. I check the tire pressure at least weekly as we all should before riding. Happy New Year!
That's good practice. I don't obsess over fractions of a PSI, but I do check before I leave that the pressures are reasonably close to where they should be.
I think consistency is the key.... get it close to what the manual recommends, adjust to your feel or desire. Then recheck with your favorite gauge then stick to that same gauge.... thx for the video, riding season can't come soon enough as our area just received a foot and a half of snow yesterday.... :(
i was always told check pressure cold. you rode your bike, and it's in a cold garage, as you checked the gauge the tire was cooling and losing air. good video, i have a stick gauge, might have to buy somthing else to compare and to be safe
These tests were actually done at a stable temperature. As I mentioned at 1:36, I only took the bike to the top of the driveway and back, which is not enough to heat up the tires. Incidentally, it isn't that a tire loses air when cooled down, it's that the air in the tire cools and contracts, which leads to a lower pressure. When you do go for an extended ride, the difference in pressure as the tire heats up is typically only about 1 to 3 PSI.
Thanks John, good video. I usually use the bicycle pump, so it appears I should stop doing that. By the way, I've relied on a number of your videos for Bonneville maintenance, and I need to do the 20,000km service on my Bonneville, and I'm up to the part where I need to grease the headstock bearings. If you've got nothing better to do there in the cold.... :)
Yeah, those bike pumps are not so great! I'm going to pick up some more of those shorty stick gauges, since they are so easy to carry. Great idea on the head bearings, I will put that on the list!
Hi - thanks for the video. A lot of dial “analog” gauges can be opened and adjusted to a known accurate gauge. What engine guards are those on your RT? Thanks
Like the digital gauges the TPMS relies on a battery, I've noticed the one on the front tyre of my GS now takes a little longer to register. Generally I check the tyre pressures before riding from my home with a MotionPro digital gauge same as the one you used and found that very comparable to the TPMS reading.
Obviously you have to have the sensor out of the wheel, but then it's just a matter of digging out the epoxy and replacing the watch battery. The second half of this video shows the whole process: ruclips.net/video/xAiJy4ZC-u4/видео.html
Excellent showdown between the TPMS and a host of tire gauges! Folks it is ironic that the SIMPLEST tire pressure gauges yielded the most consistent results, and closest to what the BMW's TPMS indicated. But that does not imply that 'all stick/pencil gauges are created equal'. If you're in a part store at the register, paying for car wash supplies, or a nice new torque wrench, and you impulse buy one of the $1.99 tire gauges hanging from the peg board at the checkout counter, you'll get what you pay for. Better off diving down the tire maintenance aisle, where all the air pumps and spare valve caps are, and picking out a stick/pencil gauge priced between $5-10. You'll notice the difference in construction, mechanical durability, and possibly how much easier the more expensive gauge is to read - especially during those pre-dawn tire pressure checks every month. My personal recommendations: Analog: - Milton or NAPA brand stick gauge(not every gauge in the world has to say "Slime" on it!) - Meiser Accu-Gage model dial gauge And the sleeper among analogs... Longacre Racing! Their Deluxe dial gauge is over $40, but is heavy, large, easy to read, and repeatable readings. I don't know how so few people know about their gauge lineup? Digital: - DIYco and JACo make a 0-200 PSI digital model, very similar features, including different scales(PSI, kPA, Bar), and high resolution - down to 1/tenth PS. - Longacre Racing - For about $10-20 more than the above two, Longacre's Basic Digital feels a little bit better built, but again, BASIC: a small non-illuminating display, resolves down to one/fifth PSI, and also reads kPA & Bars. I own Meiser's 5-60psi Accu Gage, Longacre's Deluxe, and all of the digital models above, and three or four pencil gauges, including a Milton which feels like it might be as old as me! It reads up to 3PSI different every time, and its measuring rod wiggles around a lot. I would buy a new Milton stick, but I'd rather buy it in a STORE instead of online. I have a new NAPA 5-50psi pencil gauge that seems to read pretty consistently. To me, getting a positive seal on a tire valve stem is the most important part of getting an accurate reading from any gauge. If your tire pressure adjustment sessions sound like more air hissing from your tires than snake feeding time at the zoo, you're probably doing something wrong! It could be just me, but I feel the car rides the best, most solidly, after adjusting my tires with the stick gauges. They're simple instruments, and they don't sacrifice a lot of air every time a reading is taken. Unlike most folks, I venture toward the cold tire pressures on my car door frame sticker, or 1-2psi above. On the tires I've had on the car for a year and a half, my tread wear is within 1mm even across all four tires - 5-6mm. So I guess my alignment and pressures are all good!
i'm not surprised that the analog gauges don't perform that well. manufacturing accurate analog gauges in this day and age costs money. i have a pretty good stick gauge but the biggest challenge is not to lose the damn thing. for me the recommended bmw front tyre pressure is a bit high because the bike understeers too much for my liking. thanx for the vid.
Thanks for this. I just ordered a bike pump, and I noticed it was 5psi under my old stick gauge. Not as bad as yours, but I think these bike pumps are pretty bad for the most part. To bad, because it would be very convenient for me. Know any higher quality floor pumps with a good gauge?
@@tinderboxarts I might end up doing that. But, I called a local bike shop today and they said they have one that is digital and the head bike mechanics have been using it for a while. The head guy has 40 years experience so I trust him. They said it was accurate. Didn't ask what brand yet, other than it was 65 bucks. Going to check it out Monday. I'll keep you posted. Thanks for the reply!
@@tinderboxarts Are there accurate gauges that also have a button to release air? so i can use the bike pump to over inflate it and then release until right pressure?
Yes, the act of measuring itself can reduce pressure because the tool uses a small amount of air, But, perfect test accuracy isn't really the point of this video. Instead, I was just trying to show that we shouldn't be obsessing over the air pressure numbers or a particular type of gauge. The accuracy of these gauges is a relative thing and for street riding getting close is good enough. Put another way: the perfect is the enemy of the good.
@@tinderboxarts i should've tried replacing the battery or at least reinstall it before I trashed it. It was cool see the pencil gauges were measuring the psi
Well, that's true. Really the point of the tire pressure sensors in my view is not accuracy, but an early warning system for impending doom. If you see the pressure going down while you are riding you'll have time to pull over.
So bottom line is None of the gauges are accurate. There is no way to determine a True baseline for a standard of comparison. Sure you can get a general determination of air pressure but that don't really help if your tire needs to be at a specific pressure say for getting the best gas mileage.
Well, it's not all doom and gloom. By utilizing several gauges you can get an idea when there is an outlier and then toss that gauge. And, it's important to understand that the tire pressure is not NASA style mission-critical. A couple of pounds of pressure up or down is not the end of the world. Once you become accustomed to a bike you get a feel for the pressure which works best for your riding style and your mileage or tire wear. The universal rule of thumb is 36 PSI up front and 42 PSI in the rear. You can start there and move up or down a few pounds to make the bike handle well for you. So, the actual pressure reading may not be objectively correct, but the relative difference using your gauge or gauges is still valid.
TPMS is generally NOT very accurate: * The TPMS standard specifies pressure as 2.5 * (an 8 bit unsigned number) in kPa. So if you read the pressure in kPa it will jump 2.5 kPa at a time. In PSI, that's almost +/- 0.4 PSI * The sensors aren't all that accurate either. I've not seen an actual spec, but various tests show variance of up to 3% of the reading. At 38 PSI, that's another +/- 1.14 -- so now we're at +/- 1.5 PSI * Then there's the impact of temperature. From freezing to hot, that's another few PSI. So, I would not use your TPMS as a gold standard :)
Yes, the TPMS sensors are not there for accuracy, they are there to alert you when there is a sudden drop in relative pressure, indicating an oncoming flat or blowout.
You may be missing the point, though. There are absolute measurements and relative measurements. The reality is that the inexpensive consumer pressure gauges that we can buy from retailers are never going to offer perfect pressure measurements in absolute terms. Sure, you might stumble across one which happens to offer very good accuracy in absolute terms, but that will be dumb luck and you will have no way to verify the accuracy anyway! Only with expensive scientific-industrial equipment could you verify a reading in absolute terms. However, if you compare a handful of the inexpensive consumer gauges and find that most of them agree, then you can discard the outliers and use the more accurate models. Now you have a couple gauges which will be accurate in RELATIVE terms. Perhaps you find with a little experimentation that 38 PSI in the front and 41 PSI in the rear works best for your riding. Is that 38/41 reading the actual or absolute pressure reading? Probably not. But, if you are using your most reliable gauges you can repeat those relative readings and add or subtract air as needed. You might actually be running a 36/39 pressure, but it won't matter because you found the pressure which works best for you and you can repeat the setting using the gauge(s) which will be reliable in a relative sense.
Yeah, those sensors really aren't there for perfect accuracy, they are there to get your attention when there is a sudden pressure loss or when you've forgotten to check your tires after a long period.
How does reading them all a second time make it anymore accurate. You’re still losing air everytime you put a gauge on there. And you still don’t know which one was right.
The point of the video was not absolute scientific accuracy, but a relative comparison among gauges. The second round of tests started at a slightly lower pressure for sure, but the relative results were the same. If I had found different relative results on the second round it would have indicated a problem with my readings. Keep in mind that if I take the same gauge and do ten readings from a calibrated, stable source it likely would not give me the same reading ten times. Common gauges just aren't that perfectly accurate. So my goal was to see if there was a similar range of accuracy with certain types of gauges, which there was. The outliers are the ones to be concerned about. And we learned that cost or fancy electronics are not necessarily better than a cheap mechanical gauge.
Depending on the year of your RT the TPMS display is temperature compensated (see a somewhat confusing description in the manual). So a compensated reading of 37 degrees does not directly equate to a gauge reading...unless the ambient temperature is the same as the bike uses for that measurement. Ex: If the ambient air temp is 50 when the tire is filled to 36lbs...the TPMS will read a higher pressure.
It would be interesting to take those gauges to a shop that has a calibrated gauge and test against that. That will be a good indicator of the comparison stability. There are NIST certifications for gauges but that's usually overkill for tire gauge. However buying a gauge that conforms to ANSI B40.1 is a good bet
Yes, that's right. But, the temperature compensation really comes into play in more extreme temps. I purposely ran this test in a heated garage where it was in the low 60s F. Maybe not perfectly aligned with the sensor, but pretty close. A tire running on the highway in summer temps can easily go north of 100 degrees F. Really the takeaway for me is not to put too much trust in any one gauge or sensor and to check them against each other once in a while. We'll never get perfect accuracy in consumer grade gauges.
Awesome video, it is nice to see the differences between all of the gauges
Cool video! Thanks for posting this!!
Thank you so much for this video. This is the ONLY one that cooled my anxiety about effectively reading psi
Stay calm, and ride on!
Great video. I would say there is a difference between Accuracy and Precision. Outliers that are still precise even though not accurate, may continue to be used. Just write the calibration on it with a sharpy, Example Slime gauge -5, means it reads 5 degrees lower than actual. Another test that would be interesting for those of you that live in areas with large temperature changes is testing these gauges inside at 20C/70F vs. outside at -10C/20F, to see how it affect reading, using cars that are acclimatised to their environments (not moving an inside car out for example)
Agreed--if the gauge is consistent it's still usable.
Great comparison. I only rely on the TPMS on my 2014 R1200RT while riding and use a digital when at home for a more accurate check. I carry a battery powered air pump that has been accurate and handy if I or fellow rider needs air. I check the tire pressure at least weekly as we all should before riding. Happy New Year!
That's good practice. I don't obsess over fractions of a PSI, but I do check before I leave that the pressures are reasonably close to where they should be.
Really appreciate your effort thanks
I think consistency is the key.... get it close to what the manual recommends, adjust to your feel or desire. Then recheck with your favorite gauge then stick to that same gauge.... thx for the video, riding season can't come soon enough as our area just received a foot and a half of snow yesterday.... :(
Yes, well said. And I feel your pain on the riding season--we've had snow and ice and salt and a bunch of miserable riders!
By the stains on the floor ,I'd say you own a Harley also
Ha! Probably from my Jeep. It likes to mark it's territory.
i was always told check pressure cold. you rode your bike, and it's in a cold garage, as you checked the gauge the tire was cooling and losing air. good video, i have a stick gauge, might have to buy somthing else to compare and to be safe
These tests were actually done at a stable temperature. As I mentioned at 1:36, I only took the bike to the top of the driveway and back, which is not enough to heat up the tires. Incidentally, it isn't that a tire loses air when cooled down, it's that the air in the tire cools and contracts, which leads to a lower pressure. When you do go for an extended ride, the difference in pressure as the tire heats up is typically only about 1 to 3 PSI.
Thanks John, good video. I usually use the bicycle pump, so it appears I should stop doing that. By the way, I've relied on a number of your videos for Bonneville maintenance, and I need to do the 20,000km service on my Bonneville, and I'm up to the part where I need to grease the headstock bearings. If you've got nothing better to do there in the cold.... :)
Yeah, those bike pumps are not so great! I'm going to pick up some more of those shorty stick gauges, since they are so easy to carry. Great idea on the head bearings, I will put that on the list!
Great video.
Bad example using BMW being accurate.
I've owned BMW Cars and none were great examples of accuracy in or reliability. Lol
Hi - thanks for the video. A lot of dial “analog” gauges can be opened and adjusted to a known accurate gauge.
What engine guards are those on your RT?
Thanks
Those are the same style sold by Wunderlich, but I found them on ebay. They are widely available.
Ya you just open or close the little thingy "U" shaped thing inside the round gaudes to calibrate them. A fun winter night project
Like the digital gauges the TPMS relies on a battery, I've noticed the one on the front tyre of my GS now takes a little longer to register. Generally I check the tyre pressures before riding from my home with a MotionPro digital gauge same as the one you used and found that very comparable to the TPMS reading.
Yeah, I've replaced my batteries in the sensors. You can definitely tell when they are getting weak by how long they take on initial register.
@@tinderboxarts Are they easy to replace? Have you done any videos on this? Thanks
Obviously you have to have the sensor out of the wheel, but then it's just a matter of digging out the epoxy and replacing the watch battery. The second half of this video shows the whole process:
ruclips.net/video/xAiJy4ZC-u4/видео.html
Excellent showdown between the TPMS and a host of tire gauges!
Folks it is ironic that the SIMPLEST tire pressure gauges yielded the most consistent results, and closest to what the BMW's TPMS indicated. But that does not imply that 'all stick/pencil gauges are created equal'.
If you're in a part store at the register, paying for car wash supplies, or a nice new torque wrench, and you impulse buy one of the $1.99 tire gauges hanging from the peg board at the checkout counter, you'll get what you pay for. Better off diving down the tire maintenance aisle, where all the air pumps and spare valve caps are, and picking out a stick/pencil gauge priced between $5-10. You'll notice the difference in construction, mechanical durability, and possibly how much easier the more expensive gauge is to read - especially during those pre-dawn tire pressure checks every month.
My personal recommendations:
Analog:
- Milton or NAPA brand stick gauge(not every gauge in the world has to say "Slime" on it!)
- Meiser Accu-Gage model dial gauge
And the sleeper among analogs... Longacre Racing! Their Deluxe dial gauge is over $40, but is heavy, large, easy to read, and repeatable readings. I don't know how so few people know about their gauge lineup?
Digital:
- DIYco and JACo make a 0-200 PSI digital model, very similar features, including different scales(PSI, kPA, Bar), and high resolution - down to 1/tenth PS.
- Longacre Racing - For about $10-20 more than the above two, Longacre's Basic Digital feels a little bit better built, but again, BASIC: a small non-illuminating display, resolves down to one/fifth PSI, and also reads kPA & Bars.
I own Meiser's 5-60psi Accu Gage, Longacre's Deluxe, and all of the digital models above, and three or four pencil gauges, including a Milton which feels like it might be as old as me! It reads up to 3PSI different every time, and its measuring rod wiggles around a lot. I would buy a new Milton stick, but I'd rather buy it in a STORE instead of online.
I have a new NAPA 5-50psi pencil gauge that seems to read pretty consistently. To me, getting a positive seal on a tire valve stem is the most important part of getting an accurate reading from any gauge. If your tire pressure adjustment sessions sound like more air hissing from your tires than snake feeding time at the zoo, you're probably doing something wrong!
It could be just me, but I feel the car rides the best, most solidly, after adjusting my tires with the stick gauges. They're simple instruments, and they don't sacrifice a lot of air every time a reading is taken. Unlike most folks, I venture toward the cold tire pressures on my car door frame sticker, or 1-2psi above. On the tires I've had on the car for a year and a half, my tread wear is within 1mm even across all four tires - 5-6mm. So I guess my alignment and pressures are all good!
Thanks🙏 very informative and articulate
Nice data collection thanks.
Each time you measure the pressure the air comes out, to the reading gets lower✌️
Yes, I did cover that at 6:50.
i'm not surprised that the analog gauges don't perform that well. manufacturing accurate analog gauges in this day and age costs money. i have a pretty good stick gauge but the biggest challenge is not to lose the damn thing. for me the recommended bmw front tyre pressure is a bit high because the bike understeers too much for my liking. thanx for the vid.
Thanks for this. I just ordered a bike pump, and I noticed it was 5psi under my old stick gauge. Not as bad as yours, but I think these bike pumps are pretty bad for the most part. To bad, because it would be very convenient for me. Know any higher quality floor pumps with a good gauge?
You know, I think they all are pretty poor. But, you can use the pump and just check it with a separate gauge.
@@tinderboxarts I might end up doing that. But, I called a local bike shop today and they said they have one that is digital and the head bike mechanics have been using it for a while. The head guy has 40 years experience so I trust him. They said it was accurate. Didn't ask what brand yet, other than it was 65 bucks. Going to check it out Monday. I'll keep you posted. Thanks for the reply!
@@tinderboxarts Are there accurate gauges that also have a button to release air? so i can use the bike pump to over inflate it and then release until right pressure?
Ya may wanna redo this test with an air source which has larger capacity. When I repeatedly check my front tire, I can measure the pressure drop.
Yes, the act of measuring itself can reduce pressure because the tool uses a small amount of air, But, perfect test accuracy isn't really the point of this video. Instead, I was just trying to show that we shouldn't be obsessing over the air pressure numbers or a particular type of gauge. The accuracy of these gauges is a relative thing and for street riding getting close is good enough. Put another way: the perfect is the enemy of the good.
@@tinderboxarts You uncovered the bicycle pump gauge, Slim, Inflator and the Stick 1 outliers, which is the most important point here.
That husky one was alright I used it for like 5 months then all of a sudden it started reading 2x the PSI higher than it was so it no longer turns on
Mine is still going and I've purchased several others. Possibly the battery in yours just died. Did you attempt to replace it?
@@tinderboxarts i should've tried replacing the battery or at least reinstall it before I trashed it. It was cool see the pencil gauges were measuring the psi
Of course, nothing says the built-in deluxe Grand Touring model on your Beema is correct..
Well, that's true. Really the point of the tire pressure sensors in my view is not accuracy, but an early warning system for impending doom. If you see the pressure going down while you are riding you'll have time to pull over.
So bottom line is None of the gauges are accurate. There is no way to determine a True baseline for a standard of comparison. Sure you can get a general determination of air pressure but that don't really help if your tire needs to be at a specific pressure say for getting the best gas mileage.
Well, it's not all doom and gloom. By utilizing several gauges you can get an idea when there is an outlier and then toss that gauge. And, it's important to understand that the tire pressure is not NASA style mission-critical. A couple of pounds of pressure up or down is not the end of the world. Once you become accustomed to a bike you get a feel for the pressure which works best for your riding style and your mileage or tire wear. The universal rule of thumb is 36 PSI up front and 42 PSI in the rear. You can start there and move up or down a few pounds to make the bike handle well for you. So, the actual pressure reading may not be objectively correct, but the relative difference using your gauge or gauges is still valid.
TPMS is generally NOT very accurate:
* The TPMS standard specifies pressure as 2.5 * (an 8 bit unsigned number) in kPa. So if you read the pressure in kPa it will jump 2.5 kPa at a time. In PSI, that's almost +/- 0.4 PSI
* The sensors aren't all that accurate either. I've not seen an actual spec, but various tests show variance of up to 3% of the reading. At 38 PSI, that's another +/- 1.14 -- so now we're at +/- 1.5 PSI
* Then there's the impact of temperature. From freezing to hot, that's another few PSI.
So, I would not use your TPMS as a gold standard :)
Yes, the TPMS sensors are not there for accuracy, they are there to alert you when there is a sudden drop in relative pressure, indicating an oncoming flat or blowout.
2PSI is a lot for people who care and feel 2 PSI difference.
You may be missing the point, though. There are absolute measurements and relative measurements. The reality is that the inexpensive consumer pressure gauges that we can buy from retailers are never going to offer perfect pressure measurements in absolute terms. Sure, you might stumble across one which happens to offer very good accuracy in absolute terms, but that will be dumb luck and you will have no way to verify the accuracy anyway! Only with expensive scientific-industrial equipment could you verify a reading in absolute terms.
However, if you compare a handful of the inexpensive consumer gauges and find that most of them agree, then you can discard the outliers and use the more accurate models. Now you have a couple gauges which will be accurate in RELATIVE terms. Perhaps you find with a little experimentation that 38 PSI in the front and 41 PSI in the rear works best for your riding. Is that 38/41 reading the actual or absolute pressure reading? Probably not. But, if you are using your most reliable gauges you can repeat those relative readings and add or subtract air as needed. You might actually be running a 36/39 pressure, but it won't matter because you found the pressure which works best for you and you can repeat the setting using the gauge(s) which will be reliable in a relative sense.
Very true, I agree and that is how I do it my self. @@tinderboxarts
I'd say your BMW TPM s is off
Yeah, those sensors really aren't there for perfect accuracy, they are there to get your attention when there is a sudden pressure loss or when you've forgotten to check your tires after a long period.
I believe they are temperature compensated. See the owner manual
How does reading them all a second time make it anymore accurate. You’re still losing air everytime you put a gauge on there. And you still don’t know which one was right.
The point of the video was not absolute scientific accuracy, but a relative comparison among gauges. The second round of tests started at a slightly lower pressure for sure, but the relative results were the same. If I had found different relative results on the second round it would have indicated a problem with my readings. Keep in mind that if I take the same gauge and do ten readings from a calibrated, stable source it likely would not give me the same reading ten times. Common gauges just aren't that perfectly accurate. So my goal was to see if there was a similar range of accuracy with certain types of gauges, which there was. The outliers are the ones to be concerned about. And we learned that cost or fancy electronics are not necessarily better than a cheap mechanical gauge.