Win the debate - pressure effect on tyre rotations

#rollingradius
If you reduce tyre pressures, then does it affect rolling radius - or more specifically, if you drive 50m at 50psi, will your tyre rotate the same amount of times as if you drove at 10psi? Does the effective tyre circumference change with tyre pressure?
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[@L2SFBC]

Comments on comments: 1. What about the effect of traction? Covered here in sand, it's actually more reduced rolling resistance in compression terrains kzbin.info/www/bejne/q3-ThZlomr6De5o 2. How much does the contact patch change with pressure? All explained here. kzbin.info/www/bejne/qaGyhpaXit98frs

[@gordonflash8976]

Yeah I hear you, though traction is not the same as rolling resistance. Agreed you get more grip with lower pressures say in sand, but the reason you don’ t get the traction in sand with high pressures because the resistance is lower with those higher pressures. And imagine how long his video would have been if he covered all other related topics. I’m sure he knows about lowering tyre pressures when on sand.

[@kennethprocak5176]

@@gordonflash8976the lower pressure produces a bigger contact patch thus creating a larger friction area. You’re confusing yourself.

[@gordonflash8976]

@@kennethprocak5176I do not think my comments are at odds with your own. Maybe you did not see what i was getting at. Note. rolling resistance is affected by more than just tyre pressures, thus rolling resistance will not always follow tyre pressures. Like wise traction/grip measurements will not always follow/track with tyre pressures. To express this in application, race track (tar) and/or rally drivers (dirt) get more grip from higher pressures. Drag racers (tar) and 4wd's (dirt) get more grip from lower pressures. Cheers.

[@mtower235]

The amount of ground clearance lost was surprising. I woulda guessed half that

[@off-roadingexplained8417]

So I was just lifting weights while I was listening to this video and I was thinking to myself... you know... this is a good test of a video... If you can understand what's going on just by listening to it without even watching the video... It's pretty good!

[@goldcountryruss7035]

The variations in 50# test is caused by not driving in a straight line. The slight curves resulted in a longer travel distance.

[@johndobbyns8651]

Tyre rolling circumference remains fairly consistent with modern radial tyres as their inflation pressure or tread wear changes. Their steel or polyester/rayon belts resist elongation (stretching) quite well as the inflation pressure is changed (though every material elongates under load, sometimes it is imperceptible depending on what Engineers call Modulus of Elasticity or Young's Modulus). The tyre deforms as it comes into contact to the road where it becomes relatively flat. As it does the tread blocks flex so that in the road contact patch the tread blocks are in alignment with the aforementioned steel or polyester belts, thus the circumferential length of the belts govern the rolling circumference of the tyre. Having said that, in the USA some years ago the required new cars to warn the driver if a tyre, or tire, inflation is too low. As I understand some manufactures can do that by comparing the data from the wheel speed sensors, so there must be some measurable variation of rolling circumference with respect to inflation pressure. I must commend you with the thoroughness of your video content and the range of interesting 4x4 topics that you cover. Please keep up the good work.

[@GaryL3803]

You are correct that the wheel speed sensors are used for TPMS, for Honda at least. I have a "racing" 2024 Honda Civic Type R that I drive daily and some weekends on a track at speed. The TPMS gives a false "low pressure" warning at almost every track session due to the side-to-side pressures changing since there are more right than left turns that heat the right side tires more when driving a road track clockwise. Never have gotten this when driving around off of the track.

[@danburch9989]

Very interesting test! Playing with the numbers: the differences in circumferences is very close to 1% the differences in tire rotation is very close to 1% I would estimate the difference in gas miles to be close to 1% on a hard surface. Rolling resistance on radial tires is lower than bias ply tires. The 1% differnce isn't much until you get into several hundred to several thousand miles of travel.

[@LTVoyager]

Your level of OCD matches mine. I was about to say “jack it up and align the mark” when you mentioned doing just that. 😁

[@TinkerersAdventure]

Great video! That is some nice metrology right there.

[@L2SFBC]

Thanks!

[@jamesdavidsmith4033]

Excellent, I was wondering about this.

[@m-rezaabazar-ghafari8757]

Hello MR Pepper, I love your educational, Scientific, highly valuable videos, unfortunately I do not have enough of a comprehensive language ability and words to use in order to appreciate and thanks you for all of these wonderful programs. You are a scientist super star. Much much appreciated. Thank you.

[@L2SFBC]

Thanks understood just fine!

[@kathyl67]

Great video!

[@L2SFBC]

Thanks!

[@nealesmith1873]

Great info!

[@L2SFBC]

Glad it was helpful!

[@davidholmes3323]

Should the question be does rolling circumference change. Radius will be different at three different points.

[@L2SFBC]

Rolling radius is the question, not geometric radius

[@BilletBenny]

No. Effective rolling radius is understood to be the radius of a circle with a circumference equal to the distance traveled by the tire in one rotation without slipping. So, 'effective rolling radius' is the proper engineering parameter of interest here and often it's shortened in notation to just 'rolling radius'.

[@veryaware]

I think the word “effective” was important to the plain English understanding of what was intended.

[@BilletBenny]

@@veryaware True, and officially that's the proper term. But it's typically just understood rolling radius means the same. Loaded radius is the term for the distance from the wheel center to the ground.

[@S9RUT]

Thats crazy hoe much ground clearance is lost! But i guess it is a huge difference in pressure. My Jimny muddies run 27 on the road and 12 offroad. Maybes i should consider pumping them up to 18-20 for deep ruts...

[@frodev728]

The ground clearance change will be highly influenced by the tyre sidewall profile. Specifically, a lower profile tyre (bigger wheel) will exhibit a smaller change in diameter, and therefore ground clearance between a high and low PSI, whereas a high profile tyre (which is what 4x4 enthusiasts tend to favour) will actually result in a much larger reduction in ground clearance. As with many things, perhaps extra-medium is the way to go 🙃

[@MegaLaurentd]

Interesting video as always! 👍 However, if I'm not mistaken, I think there's an error in the correction of the contact point between the wooden board and the tyre between 10psi and 50psi. The 7 cm should be added to the tyre at 10 PSI, not subtracted, because the wheel axle travelled 7 cm less (with 10 PSI) due to the longer footprint and the contact patch further forward of the wheel axle. So 1.2% and not 0.9%. Just my 2 cents for the sake of accuracy, even if it doesn't change anything to the conclusion.😉 Interesting to see that there is no difference in the number of rotations with 10 PSI as opposed to 50 PSI. Maybe that's because there's more rubber on the ground and therefore more grip with 10 PSI.🤔

[@BilletBenny]

Tire dynamics are sneakily complex. It's possible the effective rolling radius of the tire just simply changes between the two pressures. However, just as likely, and more interesting, is that the tire at the lower pressure ran at a higher slip ratio due to the increased rolling resistance and that produced the 1% difference even if the effective rolling radius remained constant. So the question is, did the test measure rolling radius or slip ratio? 🤔

[@LTVoyager]

I would have used a carpenter square to mark the tire center, but probably only off by 1/2” or less using eyeball measurement.

[@eddiereichel9354]

Some Audi vehicles actually use the wheel speed sensor for tire pressure monitor

[@aslkdfjhg]

Great work. I've heard about this in drag racing, but it has never crossed my mind in passenger cars. Imagine if our car tires deformed like dragster tyres on the highway!

[@L2SFBC]

Drag racing would also have a slip factor in as it's a driven wheel under high torque. There would be a slip factor here too as there is in any wheel, but I think it'd be negligible, not least as the wheel measure isn't driven.

[@wheater5]

I run a car that uses 5.25/16” crossply tyres. They do “grow” slightly at motorway speed, possibly as much as 1/2” in radius. I had to adjust the front mudguard fixings because I could smell rubber on the motorway. The electronic speedometer runs off magnets on the prop shaft and therefore the calibration changes slightly depending on the speed the car is doing. Confirmed by a GPS sensed Brantz trip meter over the same stretch of road, running at different speeds.

[@gordonflash8976]

@@L2SFBC You are correct with drag racing tyres and it is a large amount not negligible. One only needs to stand behind a top fuel car when it is launching to see the impressive distortion going on. It is the flex and stretch along with not braking the bead from the wheel that allows for harder take off’s.

[@StefansView]

Thanks for another interesting video! I immediately had to wonder what the outcome had been on a less flat surface. In an offroad environment with lots of bumps where the low pressure tyre can wrap around but the harder tyre hops over. Maybe an idea for a part 2?

[@L2SFBC]

The result would change in that circumstance, and also with speed.

[@cid9099]

Great timing. 👍 I just had this argument with a side by side rider. I was right, he wasn't. Thank you. 😎

[@L2SFBC]

You're welcome!

[@brunoterlingen2203]

Robert, it would have been a good exercise to measure the tyre contact patch between the two different pressures, to press home to point of "more traction".

[@L2SFBC]

Already did that kzbin.info/www/bejne/q3-ThZlomr6De5o

[@markfiddyment1948]

Running tyre pressures too low also causes more flexing in the sidewall that generates more heat and causes damage to the sidewalls. I have removed tyres that have been run to little pressure and have found a lot of rubber dust inside the tyre from the sidewalls breaking down.

[@joblogs1072]

i would have thought it would have geared it down a lot more at low pressure thus low pressure also adds to traction in addition to traction area of bagging out due to smaller circumference but 1% does not seem to indicate that. I'd like to see the same test done on soft sand and still believe it gears it down significantly. The drag resistance of 35s compared to 33s and 31s would also be interesting.

[@philg2468]

Regarding rolling resistance, you've measured the increased resistance on bitumen, which is a high grip surface. It would be interesting (but very difficult to measure) on sand or other low grip surfaces. My "seat of the pants" says that people running higher than usual pressures use more fuel than people using lower pressures on desert crossings.

[@L2SFBC]

That's slip ratio and yes it's greater on loose surfaces like sand. Another time...

[@GS-lh2nx]

I was wondering about this for awd systems. If tires are slightly mismatched in the wear patterns would keep the front at a different pressure than the rear compensate for the difference in circumference and prevent damage to the differential?

[@L2SFBC]

Yes in theory but the other problem you'd get is that the diameter changes with speed - and it changes at a different rate and distance compared to tyre pressure. So the change in a 25psi tyre from 20-100km/h would be different to a 40psi tyre from 20-100km/h. Then there's treadwear...

[@robertlindsay9826]

No. My Dodge pickup , one day abs light and low Tyre pressure light comes on. Inflate the soggy Tyre and they go off. It makes sense. Abs sensors count wheel Rev with what they call a tone ring, so if a wheel is soggy , it shows up

[@4bnewb969]

Hi Robert another interesting test. If you assume the tyre doesn’t stretch, dropping the pressure there is also some lateral deformity which takes a small measure from the circumference. I am thinking this will be the reason for the slight increase in the rotation number for the given distance. Cheers

[@veryaware]

The gaps between the tread blocks are smaller at the contact point when the tire is squashed. I think the is what allows the circumference to reduce slightly when deflated.

[@kadmow]

- and if we assume the 1% difference is purely tyre stretch - there is the variation?? maybe - assumptions ... (the flat tyre is still rolling at 1:1 tread - track - length to rim rotation)

[@davidholmes3323]

A tyre is circular in look but not really a circle when fitted to a vehicle due to deflection. I get the arguement.

[@DGB.]

You should repeat this test with bias ply tires. The effective radius & circumference will change quite a bit more than with the radial tires.

[@gianfrancoingegneri3291]

Hi, not exactly what you're talking about but i have a small camper trailer 800kgs unloaded and it's due for new tyres, would you recommend LT tyres or maybe just HT or AT? it will be 80% on road 20% unsealed, dirt, beach driving. Thanks.

[@L2SFBC]

HT should be fine. The main advantage of LT is puncture resistance but with that light weight and therefore low pressure risk of punctures is low.

[@gianfrancoingegneri3291]

thanks, so fairly flexible for my situation i understand.@@L2SFBC

[@vincentrobinette1507]

One last experiment: measure axle height unloaded, then, put 500 kilograms of load over the rear axle and measure the difference. I'll bet there will be less change in rolling radius, when inflated to vehicle recommended pressure. If over-inflated, the height will actually change MORE from no load to full load. you may or may not find the same thing, if underinflated.

[@jimsix9929]

as a quarter mile drag racer here in Ohio USA, I can tell you it comes down to the distance from the center of the axle to the pavement, yes tire pressure will change that

[@r.k862]

So if I'm roll race will a lower psi tyres be quicker in acceleration vs a high psi tyres? My car is not high powered so I don't care about traction as much

[@jimsix9929]

@@r.k862 lower tire pressure will give you a lower overall gear ratio, more traction and more engine RPMs, so yes a bit faster off the line, but at the expense of fuel economy and cornering, also tire wear may be affected, depends on the cars gearing, RPMs = horsepower but if you already have low gearing it will not help much

[@r.k862]

@@jimsix9929 so lower tyre pressure is only good off the line or is it also good at accelerating after the take off?

[@jimsix9929]

@@r.k862 yes only good for a good start, as soon as the advantage of better traction and a lower gear are gone you will go faster with higher pressure

[@r.k862]

@@jimsix9929 thanks. My car placard says about 37psi is recommended. If I am not looking for traction but I am looking for fast acceleration what max psi should I set it at?

[@55Agro]

Reduced pressure reduces clearance by increasing the flat spot. That flat spot is cut from the unloaded circumference, hence the small increase in rotations. Only possible necause of comptession &/or closure of the tread. Not enough to alter the speedo, but rolling resistance & heat build up is another league.

[@maxgood42]

13:20 should be taking 70mm away from 50PSI or adding 70mm to 10PSI but I don't think it would make a huge difference anyway as you have clearly shown here. Great way to show that the car is still traveling on the belt as if we went by the clearance change from 223 to 170 as the change of radius then our calculations would get about 15.2% difference in distance ( Diameter of 802.8 = Circumference of 2522 / 802.8 - 53x2 (53 theoretical radius) = Diameter of 696.8 = Circumference of 2189 (difference of 333mm)) ... (50000mm / 2522 = 19.82.... 50000 / 21890 = 22.84.... 100/19.82=5.0454...... X 22.84 = 115.23.....) And you obviously did not cut this out of your tread to make up the difference so where did it go? "Rolling Resistance" as the tread was constantly grinding from the front of the contact patch to the back before leaving the road This can be seen if you ever had to shift a car on dirt or sand with flat tires and no motor, the tracks often leave a strange pattern in the middle as if the tires were completely bald .

[@AlienLivesMatter]

1% Rolling circumference decrease and rolling resistance increase 13%

[@kennethprocak5176]

Just measure the circumference with a piece of string, at 50psi then at 10psi, the tyre should balloon very slightly had higher pressure giving a greater circumference.

[@ranger178]

I like to fill my tires to a bit higher than recommended pressure mid-day when warm out just a couple pounds since the recommended pressure says cold i figure set it to coldest temperature in the mornings plus an extra pound since tires are always losing air. the actual tire pressure changes constantly 1 psi per 10 degrees roughly so it is all relative to speed you are driving weather all that, so I always wondered if you are a few pounds low or a few pounds high does it make much difference in stopping distance and cornering as well as grip when you accelerate have you tried testing the stopping distance or things like that at various pressures?

[@GaryL3803]

When racing a 2 PSI difference can definitely be both sensed by the handling of the car and measured in lap times.

[@ranger178]

they say fill car for cold temp, so I try to set it for what it is at coldest temperature in morning since it changes about 1 psi per ten degrees and in my manual, it actually recommends an extra pound pressure if you are driving at high highway speeds you could have 6 psi change from cold tires undriven in morning to hot afternoon tires after high-speed driving.so hard to figure what is the right pressure?@@GaryL3803

[@gordonflash8976]

I have never worn out the centre of a tyre running higher pressures. For the reduction in comfort experienced, while all other performance metrics are improved, I think it is better to run slightly higher pressures than recommended.

[@kadmow]

- and if you like cornering a little energetically increased pressure will tend to even out the apparent scrub wear.. matbe..

[@julesviolin]

Yep I've run 4psi over the recommendation for 45yrs and tyres don't wear on the edges so much. As much as 10k miles can be gained ⚠️ It's a trade off however as there is less grip but I've never been a boy racer but massive savings made on tyre expenses 😊

[@supersportimpalass]

Narrow tires aren’t affected as greatly but it is noticeable the wider the tires the more you have to watch tire pressures. Over inflated wide tires will significantly decrease life of a tire.

[@gordonflash8976]

@@supersportimpalass yep, I agree, I guess that is the price of fashion.

[@gordonflash8976]

@@julesviolin agreed accept for the reduction in grip part, where I would say that when braking you actually have more grip as stopping distances are shown to reduce. When turning hard you have more grip only on the wheels that have increased weight on them. When turning tyres on the spot in say a car park you have less grip and this is when you want less.

[@insanelysane86]

Interesting findings, goes to show a hypothesis should always be tested! I always assumed a deflated tire worked as a track, and the effective circumference was the same regardless of tire pressure. Because the change is so small ~1% it would seem the difference is most likely due to an increase in rubber stretch from the pressure at 50 psi? Did you measure the tire with tape at both 50 and 10PSI? It would also be interesting to see another PSI data point, perhaps one where the tire carcass isn't deformed to the point of the sidewall making contact with the ground; there is a possibility that having so much deformation causes other interesting physics to happen to the tire as it rotates.

[@L2SFBC]

No, just measured it unladen at road pressure. Can't put everything into one video!

[@xZeiZeix]

Tires track surface doesn't shrink in lower psi, but it buckles up in ground contact, as it has nowhere else to go.

[@insanelysane86]

That makes sense, I think you may be right.@@xZeiZeix

[@nicknick7052]

Where did you make this video? Are you in Australia?

[@orangejuicepony6881]

Melbourne Vic

[@L2SFBC]

In the Australian outback, it's a lie that it's all dirt, it's actually concrete.

[@nicknick7052]

@@L2SFBC

[@leodepaz1963]

That's awesome but it would be much better if you do that on actual sand so we can see the actual width but also the depth of the tyres on sands. We're not deflating on roads or cements but on sands and muds...

[@L2SFBC]

Then we get tyre slip...

[@mikehzz9848]

You didn't measure the radius from the centre of the wheel to the ground. The difference in rotation speed is a function of that radius and the wheel will rotate faster if the radius is smaller. Tyre pressure warning systems use this principle to tell when a tyre is going down.

[@L2SFBC]

I did, I just didn't put that in due to timing. 368 and 310mm is your answer.

[@davidberry2542]

Well as I watched this video I was sure you got the results wrong. I was thinking with a 55mm reduction in radius, which is more than 10%, the distance travelled per wheel revolution should also reduce by more than 10%. I figured you had miscounted the total number of revolutions between the 10psi and 50psi tests. But I watched and counted the revolutions and it seemed your counting was accurate. My head was hurting as this just wasn’t making sense. So to make sense of what is going on here I reckon you can think of a tyre tread as a track (as in bulldozer track) of a particular length and just about disregard everything else (such as pressure reduction and sidewall deflection). For each rotation of the track (tyre tread), it moves the vehicle forward by approximately the circumference of the tyre, no matter the tyre pressure. Thanks heaps for your interesting and educational video, greatly appreciated!

[@L2SFBC]

I deliberately left the "why" out of this one, might do that soon :-) And that is why I put the runs in so you can see for yourself, no trickery! Yes the effective circumference changes. Think about a massively overinflated tyre...where does it wear? Then think about an massively under-inflated tyre...where is the wear pattern on that?

[@garreysellars5525]

While you are at it measure yread width and compare with advertised width especial different brands More so with truck tyres Reputable brands measured up but cheeper brands don't Ripped off on Dollars. And SAFETY

[@L2SFBC]

The section width is overall width not tread width, common to all tyres.

[@garreysellars5525]

@@L2SFBC sorry it's not common understanding You buy a tyre based on advertised width to suit your driving style and load only to find its incorrect depending on brand Some vary as much as 45 mil. So over 4tryes that is almost 1 tyre equivalent tred width short on a 265 Compromise on SAFETY

[@jumboegg5845]

Rub the chalk off the tyre and make a new mark, its a bit easier than using the high lift jack.

[@L2SFBC]

Why do you think I didn't do that?

[@jumboegg5845]

​@@L2SFBC You thought it would actually make a difference in terms of accuracy, but of course it made no difference, just eyeballing the degree of rotation (ie 3 oclock, 9 oclock etc. would have been more than enough accuracy. Nice little chalk marks showing a tiny bit of variance betwen runs looked pretty but a lot of extra work.

[@L2SFBC]

I disagree, wanted to do it properly.

[@jumboegg5845]

@@L2SFBC Fair enough. So from your results, I calculated the circumferences as 2.43m for 50psi and 2.41m for 10 psi, which is exactly what you calculated (15:00). From these two circumferences, I calculate that the radius at 50 psi was 387 mm, and the radius at 10 psi was 384mm. Thats a tiny 3 mm difference in radius between the tyre pressures, which is not consistent with what we can see, and with what you measured in the ground clearance. Something doesn't add up, and I'm not sure where the problem lies. Can you explain it? The only explanation I can come with is that the tyre is rolling as an oval, and despite the change in tyre pressure, the circumference of the oval does not (and cannot) change. Edit. just read the comments by @johndobbyns8651and @maxgood42 below. That's what they said.

[@overlandready]

You're better off doing something like 10 ratations of the tyre and marking the ground, as a 50m run will give inherent intollerances as you fould on reversing the 50m back, any difference in the track taken will add or subtract to the measurement so the test in in essence flawed from the word go. I think you'll get less errors in a shorter run. The results though are as expected, the lower pressure effeectively lessens the distance from the centre of the wheel to the outside of the wheel, so it will take more turns to travel the same distance. I believe a better test would actually be to measure distance of x rotations rather than rotations over x distance as that gives a more accurate test. you would have to follow a line rather than free drive as your tests. The reason for this is clearly visible in your tests as you vary distance from the tape, this is creating inaccuracy of test.

[@L2SFBC]

Whether I went for a fixed distance or fixed number of rotations doesn't make a difference. With the fixed distance I could show on the tyre the differences. Can't do that with the ground version. Both are as valid.

[@overlandready]

@@L2SFBCFor accuracy, I'd have to disagree as your 50psi measurements show 3 different measurements, if the fixed distance was accurate, the mark would not differ, so the vehicle had travelled 3 different paths and 3 different distances. On rotations, you have less error possibility as it measures the distance travelled for x rotations. Thus the 10psi test will still show a difference if the effective circumfrance of the tyre is changed (which it will be) by the distance travelled. The results will still show similar results, but the point is one will give a higher accuracy on repeatability. I'd agree with you IF the 50psi tests came out almost exactly the same, but 3 tests and 3 different results is a fail of the theory of the test to me. Maybe run a rotations test on a surface dotted with sand, it'll give the ability to see how far from straight you line actually is, thus able to measure more accurately. The problem is how to remove the "human error" from the test as that is what the differnces in the 50psi test was.

[@L2SFBC]

This was not a lab-controlled test so I'm not surprised by the slight change in results. Taking a fractionally different line could be one reason. Starting and finishing at a fractionally different rotation point could be another. The list goes on. The problem with sand is that you then introduce tyre slip into the equation which on the surface tested is neglible. There are many ways to make the test more precise but given my time and cost constraints, I chose that method, and made it clear so comments like yours could be made. I would suggest that the 3x50 results were indeed "almost exactly the same" as it was.

[@overlandready]

@@L2SFBC I considered you were't happy with the tyre position on the second 50psi run, so therefore accuracy did matter, if not the near enough approach wins and that gives more inaccuracy. I would say different track is absolutely where the errors come in, it does prove though that however hard you try to keep the same line, you vary slightly. You are normally quite good at performing good semi-controlled tests, like with the pulley ring tests, They are good real world tests no matter the small inconsistancies. On something else on the video, I was quite surprised to see how much the tyre deformed on 10psi, I have BFG muds on the 110 (not by choice, but they keep the rims off the floor as it's being rebuilt, I will be running All Terrains) At 10psi the muds barely deform at all, the 110 is effectively kerb weight at the moment as it is totally empty, so about 1,700kg. out of interest how much does your vehicle weigh?

[@L2SFBC]

The vehicle weighed around 2800kg as tested there. Had some gear in the back, near full long-range tanks, so significantly more. If you run 235/85/16 on your 110 that'll be a different too, those tyres are 265/70/17 so not as tall and lower profile.

[@leejankovskis7814]

Pointless exercise unless you do it at speed. At speed the lower pressure will expand its circumference due to rotational centrifugal force and would be quite a lot bigger than the higher pressure tyre. Drag cars are a good example, they run very soft pressures and the tyres expand such a large amount they virtually become a variable final drive ratio.

[@L2SFBC]

The test was intentionally run slowly. Guess why?

[@flipcoin6301]

What’s with all that trash along the road? Looks like California.

[@L2SFBC]

flytippers unfortunately. The resident brown snakes love it though.

[@jerrymyahzcat]

The word is synced not synched. No such word as synched (said sinched).

[@chuckfinley3152]

*tire 😬

[@doneB830]

Also about 1% more torque.

[@L2SFBC]

But...rolling resistance!

[@operation4wheelz]

And butt load of resistance. I conducted a similar test but measured individual rotations rather than over larger distance. 40-5 PSI. The difference on one rotation is so negligible that it’s barely worth acknowledging its existence. I think it’s just tread blocks being squeezed into a smaller area. Ive seen other tests on road tyres and the difference was basically immeasurable. So I suspect particular tyres will vary slight in results.

[@MadMaxV]

what the hell is the point of this in a real world scenario. jesus.....

[@L2SFBC]

The real world scenario is this. Imagine a campfire. Around the campfire are your friends. You've had a hard days wheeling, bellies are full and beers are out. Some guy says I wonder if decreasing tyre pressure is the same as lowering gears? And now you know the answer and can get onto one locker, front or rear. You're welcome

[@insanelysane86]

@@L2SFBC Perfect reply!

[@TheBigRed.]

🤡🌎🥴