# Is A Higher or Lower Tire Pressure Faster?



## TehYoyo (Sep 16, 2012)

Is it better to have a higher or lower tire pressure?

I just heard that lower tire pressure is faster, but it seems (logically) to me that a higher tire pressure, i.e. less of the tire hitting the road, would be faster.

Thanks,
TehYoyo


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## tednugent (Apr 26, 2010)

there is a sweet spot for your weight and tires

too high... means tires don't track on the road too well, which means power is now getting to the ground (which has bumps and such)

too low, means too much deflection of the tire, which slows you down.


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## nOOky (Mar 20, 2009)

It is always better to have the pressure dialed in for your rim, tire, and body weight riding combination with a nod towards ambient temperature.


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## Kerry Irons (Feb 25, 2002)

TehYoyo said:


> Is it better to have a higher or lower tire pressure?
> 
> I just heard that lower tire pressure is faster, but it seems (logically) to me that a higher tire pressure, i.e. less of the tire hitting the road, would be faster.


Just for clarity's sake: if the pressure is too high, then the tire will not conform to road surface roughness and the vibrations will transmit into your body - that is lost energy so too high pressure on real-world road surfaces can slow you down. If the tire is too soft then it will flex excessively and that will waste energy that is lost in the heat of rubber and casing flex. So you look for the Goldilocks point, though the range is fairly wide. General guidance is that if you need to pump much over 100 psi to prevent pinch flats then you either need wider tires or improved riding technique.

The general downsides of too-high pressure are more rapid tire wear, rough ride, poor traction, and increased losses due to rough road surfaces.


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## kbiker3111 (Nov 7, 2006)

It depends on the smoothness of the riding surface. If you are riding on glass, the highest pressure possible is fastest. If you are riding on gravel a much lower pressure is faster.


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## cxwrench (Nov 9, 2004)

good god kid, spend some time reading the dozens and dozens of posts about tire pressure on this forum. seriously...try the 'search' function. there's probably an entire night's worth of reading just about pressure. 
it's all based on a few variables...
rider/bike weight
tire size
rim width 
and in some instances road surface condition. 
the simple answer, based on what people have been doing w/ tire pressure over the years is 'lower pressure is generally faster...to a point'. but, there are so many variables. generally, no one needs more than 100psi on the road. ever. if they weigh a lot, they need bigger tires. there are even variables on the track...concrete or wood? pursuit, sprint, or mass start? 
see what i mean?


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## TehYoyo (Sep 16, 2012)

nOOky said:


> It is always better to have the pressure dialed in for your rim, tire, and body weight riding combination with a nod towards ambient temperature.





Kerry Irons said:


> Just for clarity's sake: if the pressure is too high, then the tire will not conform to road surface roughness and the vibrations will transmit into your body - that is lost energy so too high pressure on real-world road surfaces can slow you down. If the tire is too soft then it will flex excessively and that will waste energy that is lost in the heat of rubber and casing flex. So you look for the Goldilocks point, though the range is fairly wide. General guidance is that if you need to pump much over 100 psi to prevent pinch flats then you either need wider tires or improved riding technique.
> 
> The general downsides of too-high pressure are more rapid tire wear, rough ride, poor traction, and increased losses due to rough road surfaces.


Thanks, guys. When I read a few articles, I see various PSI counts - some are around 100/110, but others talk about 40/60 load differences, which equals out to about 60/90 psi. Why the differences?


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## SauronHimself (Nov 21, 2012)

This comes down to basic physics. You start by recognizing that every tire has a flat spot where it contacts the ground, and that's because there is no such thing as a perfectly rigid object. Besides, you wouldn't want your tire contacting the ground at a single point anyway since you'd have no traction around turns. Contact friction is not a function of surface area; it's strictly a function of the normal force acting against the tire, so in that sense alone it wouldn't matter if the contact patch were larger (lower pressure) or smaller (higher pressure). However, in order for the flat spot to become round again as it rotates, energy is required. That energy ultimately gets supplied by the rider, but less has to be exerted if your tires are pumped to a higher pressure (more air forcing the tire from flat to round). This would suggest that higher pressures are better, but there is a caveat to this as well. On a road bike rim 19mm wide with a 23mm tire, that assumption loses ground above 120ish PSI. Your tire's contact patch deforms unusually and causes bouncing which, in turn, leads to what are known as suspension losses in the rider. This saps energy out of the system and actually forces you to increase your output to maintain a certain speed. This is why the advocacy towards wider rims-and-tires combinations have increased. The contact patch ends up being wider and shorter, so it doesn't deform like a 23mm tire at a higher pressure, and lower pressures can be run on the wider tire with the actual air volume comparable to the 23mm tire, but the ride on the wider tire and rim is more comfortable.


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## afiotrek (May 27, 2013)

Generally a higher pressure is going to make a faster and smoother ride. A tire that is too soft will cause more traction and thus more drag. It will also cause the bike to feel sloppy on the road. Having said all of this, never inflate a tire more than recommended (can be found on tire sidewall). As others have said the pressure should be relevant to your weight(heavier rider a little higher pressure or vice versa)


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## cxwrench (Nov 9, 2004)

afiotrek said:


> Generally a higher pressure is going to make a faster and smoother ride. A tire that is too soft will cause more traction and thus more drag. It will also cause the bike to feel sloppy on the road. Having said all of this, never inflate a tire more than recommended (can be found on tire sidewall). As others have said the pressure should be relevant to your weight(heavier rider a little higher pressure or vice versa)


i have no idea what you said in your first post but after your second i can tell you need to get a pretty big clue. your last sentence is the only one that makes any sense at all.


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## Marc (Jan 23, 2005)

TehYoyo said:


> Thanks, guys. When I read a few articles, I see various PSI counts - some are around 100/110, but others talk about 40/60 load differences, which equals out to about 60/90 psi. Why the differences?


Because of weight distribution, most of the time...a majority of your weight is loaded onto the rear axle as a function of rider position on the frame geometry.


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## froze (Sep 15, 2002)

Here's a handy dandy psi calculator, to use the calculator first go to the second one that says "total weight (bike+rider), then simply enter your fully clothed for cycling body weight PLUS the total weight of your bike ready to ride including full bottles. Next change your tire sizes to correspond to what you use. Then hit enter. Both front and rear pressures will be shown, this calculator is right for street riding to within 5 pounds on the front and rear for most people, some people may want a firmer ride and may increase it by 5psi and some may want it softer and decrease it 5psi. On the front some riders will instead use 20 pounds less on the front then rear, it's just personal preferences.

But this calculator is pretty accurate for street riding, for racing there are other factors to consider.


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## Kerry Irons (Feb 25, 2002)

froze said:


> Here's a handy dandy psi calculator, to use the calculator first go to the second one that says "total weight (bike+rider), then simply enter your fully clothed for cycling body weight PLUS the total weight of your bike ready to ride including full bottles. Next change your tire sizes to correspond to what you use. Then hit enter. Both front and rear pressures will be shown, this calculator is right for street riding to within 5 pounds on the front and rear for most people, some people may want a firmer ride and may increase it by 5psi and some may want it softer and decrease it 5psi. On the front some riders will instead use 20 pounds less on the front then rear, it's just personal preferences.
> 
> But this calculator is pretty accurate for street riding, for racing there are other factors to consider.


Is this the famous "missing link" which gets discussed so often?


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## SauronHimself (Nov 21, 2012)

I think Froze referred to this:

Bicycle tire pressure calculator


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## froze (Sep 15, 2002)

SauronHimself said:


> I think Froze referred to this:
> 
> Bicycle tire pressure calculator


Thanks, I forgot to paste it!


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## bobf (Apr 3, 2015)

Yes ... and there is a lot of room to add in personal preference. The 15% drop method suggests 70/100 psi, assuming rider plus bike plus gear weighs 220lb and tire width is 27mm (25c's on 24mm rims). But at the moment I find I'm happier at 60/90. Still experimenting, tho.

I'm with the people who say the psi sweet spot is wide. I think there is a trade between smoothness and speed, but it's reallly gradual. All of which says you need to experiment. At first I was nervous about riding on lower pressure, but with some care I managed to find my rear lower limit (80 psi is very cushy but just a tad slow) w/o getting any pinch flats.

For me, the difference between 110/110 psi and 70/90 psi is getting beat up by chip seal and floating over it. I feel just as fast either way.


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## cxwrench (Nov 9, 2004)

bobf said:


> Yes ... and there is a lot of room to add in personal preference. The 15% drop method suggests 70/100 psi, assuming rider plus bike plus gear weighs 220lb and tire width is 27mm (25c's on 24mm rims). But at the moment I find I'm happier at 60/90. Still experimenting, tho.
> 
> I'm with the people who say the psi sweet spot is wide. I think there is a trade between smoothness and speed, but it's reallly gradual. All of which says you need to experiment. At first I was nervous about riding on lower pressure, but with some care I managed to find my rear lower limit (80 psi is very cushy but just a tad slow) w/o getting any pinch flats.
> 
> For me, the difference between 110/110 psi and 70/90 psi is getting beat up by chip seal and floating over it. I feel just as fast either way.


You just managed to dig up and reply to a thread from 2 years ago. About a subject that gets discussed every week. Thanks.


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## SauronHimself (Nov 21, 2012)

cxwrench said:


> You just managed to dig up and reply to a thread from 2 years ago. About a subject that gets discussed every week. Thanks.


1. The OP is a new member as clearly shown by his post count and join date.
2. You hate it when n00bs don't use the search function and start new threads for previously discussed topics.


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## Aladin (Oct 5, 2014)

SauronHimself said:


> 1. The OP is a new member as clearly shown by his post count and join date.
> 2. You hate it when n00bs don't use the search function and start new threads for previously discussed topics.


And.. your pt? 4700 posts and your whining about a noob?

C'mon.. live and let live.:thumbsup:


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## SauronHimself (Nov 21, 2012)

Aladin said:


> And.. your pt? 4700 posts and your whining about a noob?
> 
> C'mon.. live and let live.:thumbsup:


I'm not complaining about the OP. I was telling cxwrench to cut him some slack.


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## ridesmasterx (Aug 3, 2013)

It takes more time to pump up to a higher pressure so a higher pressure is actually slower and I don't get out riding quite as quickly.


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## robt57 (Jul 23, 2011)

ridesmasterx said:


> It takes more time to pump up to a higher pressure so a higher pressure is actually slower and I don't get out riding quite as quickly.


As much as I disapprove of zombies being brought back.. 

More 'time' makes a good point. Especially when you flat on the road. @ 120 lb you never quite got back there after a flat fix, did you? [you generally].


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## Mandeville (Oct 18, 2014)

I have a Trek Domane with 25 inch tires. A very common popular tire in terms of numbers in use. The tire MANUFACTURE'S recommended PSI range is 90 to 125 pounds. According to the pressure calculator I should be running 88 pounds front and 137 pounds rear. And then there is the recommendation along with the linked gauge that if one exceeds the recommended PSI get a wider tire and if under get a narrower tire. So...according to the gauge I require much greater PSI for the rear, (far exceeding the recommended manufacture's max), and should get a wider tire and I'm a bit under the minimum for the front so I should get a narrower tire. Now I'm no authority but it's hard to have a lot of confidence in the gauge given it's findings in relation to the real world. 

(I usually ride 105 on the front and 115-120 on the rear.)


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## cxwrench (Nov 9, 2004)

Mandeville said:


> I have a Trek Domane with 25 inch tires. A very common popular tire in terms of numbers in use. The tire MANUFACTURE'S recommended PSI range is 90 to 125 pounds. According to the pressure calculator I should be running 88 pounds front and 137 pounds rear. And then there is the recommendation along with the linked gauge that if one exceeds the recommended PSI get a wider tire and if under get a narrower tire. So...according to the gauge I require much greater PSI for the rear, (far exceeding the recommended manufacture's max), and should get a wider tire and I'm a bit under the minimum for the front so I should get a narrower tire. Now I'm no authority but it's hard to have a lot of confidence in the gauge given it's findings in relation to the real world.
> 
> (I usually ride 105 on the front and 115-120 on the rear.)


You need a bigger rear tire. Or some confidence in physics. 

And new members need to learn how to use the site. Too much space is taken up by people repeatedly asking the same 3 or 4 questions over and over again every week. It's not that hard to do a little looking and reading. Good thing some of you 'sensitive' guys are on a polite bicycle forum and not some of the less touchey-feely forums that are out there.


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## Mike T. (Feb 3, 2004)

cxwrench said:


> And new members need to learn how to use the site. Too much space is taken up by people repeatedly asking the same 3 or 4 questions over and over again every week. It's not that hard to do a little looking and reading.


This is why -
1. I got the forum "stickie" and its FAQ started - that *anyone* may contribute to! But I wonder how many Newbs see it or read it?
2. I built my wheelbuilding web pages.



> Good thing some of you 'sensitive' guys are on a polite bicycle forum and not some of the less touchey-feely forums that are out there.


Oh for sure. Even I quit hanging out at Bikeforums as they don't take many prisoners there. Then there was the Digital forum that I joined for satellite TV info - I searched the archives for my answer, didn't find it and asked my question. The moderator *BANNED* me for a week - no warning; nothing! Boom. Reason - the answer was in the archives. Asking a question that's already been covered was not allowed. It was my FIRST post too. And my last.

RBR is the polite forum for sure.


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## rruff (Feb 28, 2006)

cxwrench said:


> Too much space is taken up by people repeatedly asking the same 3 or 4 questions over and over again every week.


Sometimes it takes a few thousand repetitions before the message finally sinks in...


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## Mandeville (Oct 18, 2014)

As to the OP, the only thing that I can add to my previous post is that before my getting my road bike I rode an old heavy MTB strictly on the road. I initially swapped out the conventional MTB 2 inch tires for a 2 inch road tire. Later after a great deal of trying for over a period of reasonable time for PRs on certain rides and climbs on the road I switched to 1.5 inch road tires. 

The 2 inch tires were inflated to 60-65 pounds. The 1.5 inch tires were inflated to 90 pounds. 

Overall the bike was quicker on the two-inch tires and rode better. That's just my experience in one scenario.

At one time I also did some serious research on pressure and the size of tires regarding which was best. I relied upon empirical testing results. It was an interesting and a few times contradictory -- but interesting.


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## Randy99CL (Mar 27, 2013)

cxwrench said:


> good god kid, spend some time reading the dozens and dozens of posts about tire pressure on this forum. seriously...try the 'search' function.


I'd love to see a guide to actually _using_ the search function. It could be stickied into the Beginners' Corner.

When I do a search (here or on other forums) I often get thousands of hits that would take many hours to scan. For example, typing "tire pressure" might bring up every post with "tire" or "pressure" or "tire pressure".

Are there operands that would help narrow the search?


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## Drew Eckhardt (Nov 11, 2009)

TehYoyo said:


> Is it better to have a higher or lower tire pressure?
> 
> I just heard that lower tire pressure is faster, but it seems (logically) to me that a higher tire pressure, i.e. less of the tire hitting the road, would be faster.


Rolling resistance decreases with increasing pressure; although with real roads eventually you start getting slightly airborne on minor imperfections and loosing energy.

From Slow Twitch What's in a tube?









The curve is flatter before the tire starts leaving the ground so you're better off with under-inflation than over-inflation.

The effects are also slight - dropping pressure from 7.5 bar (109 psi) to 5.5 bar (80 psi) in a 700x28 Continental GP4000SII Tour magazine measured only a 1W or 2W (text beneath the info graphic and within the article disagreed) increase in rolling resistance with a 85kg load (187 pounds) at 35 km/h (21.7 mph)

2014 Tour Magazine tire test


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## Mandeville (Oct 18, 2014)

Drew Eckhardt said:


> Rolling resistance decreases with increasing pressure; although with real roads eventually you start getting slightly airborne on minor imperfections and loosing energy.
> 
> From Slow Twitch What's in a tube?
> 
> ...


I wish I could be more specific as to what team and when for what follows but I didn't bookmark it and I don't recall the details other than:

Sometime in the not too distant past, (at 69 years old my standard for not too distant may be different than yours), a certain TDF team or TDF level team had their racing tire switched from 23mm to 21mm. I do not know the PSI for either tires. The changes were made per team management. 

The riders began to complain claiming that they were certain by feel that the 23mm were faster. Management "knew" the riders were wrong because everyone knows that thinner tires offer less resistance and are faster or some such thinking. (Again sorry for lack of specificity.) Anyway, management thought to quiet the riders and to reassure them they would conduct some scientific test and show what they were sure they all ready knew, that 21mm tires are "faster" that 23mm. The tests were conducted and showed the 23mm were faster. The team riders got their 23mm back AND a higher sense of appreciation for the ability of the pro riders to tell such a small difference from just instinct or "feel."


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## ibericb (Oct 28, 2014)

When it comes to tires and the effects of pressure, there is more to speed than just rolling resistance. At some point with increasing pressure "suspension losses" become an issue, which is NOT the tire leaving the ground. This has been well discussed in previous threads.


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## Father Guzzi Obrian (Jan 31, 2015)

Hi, 
This is Jake from State Farm. Make sure you don't make a typo on the calculator or you will need to add 234 lbs to your rear tire and may need a new pump 



SauronHimself said:


> I think Froze referred to this:
> 
> Bicycle tire pressure calculator


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