Road Bike Tire Pressure

orangebox82

Hello all,

I always assume that if the tire has more air, it means that it is going to be light and roll faster because it has more air or am I wrong?

The place I run my bike has a smooth road surface and I do not have to worry much about pot holes and such.

I am using 700x25 Continental Gatorskin/ Ksyrium Elite S and I always put 120 psi on it to make it lighter and easier to ride. now if I lower the psi from 120 to lets say to 110-100 psi will that means that I have more road surface contact and the wheel/tires feels heavy and it roll slower?

What do you guys run on a dry condition and why and is there a con and pros to having low and high psi on a tire?

Thank you!

Bobbinogs

:-)

There are a lot of threads on tyre pressure so have a go at the search tool. Given the road surfaces you enjoy then you can run a little more than most in the UK but, essentially, optimum pressure is dependent on a number of factors: weight, tyre size, etc.

Oh, more air does not make a bike lighter.

doug5_10

Google 'road tyre pressure chart', Michelin one usually comes up most often.
Rider weight probably biggest influencing factor, 25c's shouldn't need much more than 100PSI unless you're nearing 90 - 100 kg. That is the benefit of larger tyres, they can run at lower pressures, improving comfort. For instance I'm 83kg, run 23c at 105-115 and 25c at 95-105.
Pressures too low will invite snake bite punctures.
Pressures too high will give harsh ride, and you will only roll faster on the smoothest of smooth roads. i.e. a velodrome

canamdad

Some good info on tyres in this new article by Leonard Zinn from Velo News: http://velonews.competitor.com

6wheels

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19741211#p19741211]canamdad[/url] wrote:

Some good info on tyres in this new article by Leonard Zinn from Velo News: http://velonews.competitor.com

Thanks, a real in depth look at tyre pressures/resistance.

ThatBikeGuy

I run 90 psi but then I usually let it drop to about 70 before pumping them back up. I prefer the spongier ride what with the rough roads I have around my way. I'm also fairly light at ~65kg so don't worry too much about pinch-punctures.

k-dog

IME experience most people ride pressures way too high. As said already there's no need for 100+ unless you're heavy. You'll be much more comfortable and faster (due to less hopping about) at more like 85-90.

Anonymous

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19741975#p19741975]ThatBikeGuy[/url] wrote:

I run 90 psi but then I usually let it drop to about 70 before pumping them back up.

So you ride around with tyre pressures that differ by around 25%?

You must feel a difference (otherwise why not let it drop below 70 or pump up higher than 90) so would it not be best to make an effort to ride at the optimum pressure?

davidof

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19740924#p19740924]orangebox82[/url] wrote:

Hello all,

I always assume that if the tire has more air, it means that it is going to be light!

Don't pump over 150 psi or your wheels might float away!

mfin

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19741207#p19741207]doug5_10[/url] wrote:

Google 'road tyre pressure chart', Michelin one usually comes up most often.
Rider weight probably biggest influencing factor, 25c's shouldn't need much more than 100PSI unless you're nearing 90 - 100 kg. That is the benefit of larger tyres, they can run at lower pressures, improving comfort. For instance I'm 83kg, run 23c at 105-115 and 25c at 95-105.
Pressures too low will invite snake bite punctures.
Pressures too high will give harsh ride, and you will only roll faster on the smoothest of smooth roads. i.e. a velodrome

You are running pressures too high for your weight.

doug5_10

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19742895#p19742895]mfin[/url] wrote:

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19741207#p19741207]doug5_10[/url] wrote:

Google 'road tyre pressure chart', Michelin one usually comes up most often.
Rider weight probably biggest influencing factor, 25c's shouldn't need much more than 100PSI unless you're nearing 90 - 100 kg. That is the benefit of larger tyres, they can run at lower pressures, improving comfort. For instance I'm 83kg, run 23c at 105-115 and 25c at 95-105.
Pressures too low will invite snake bite punctures.
Pressures too high will give harsh ride, and you will only roll faster on the smoothest of smooth roads. i.e. a velodrome

You are running pressures too high for your weight.

I've just always gone by the Michelin chart as a guide simply because thats what came up first in Google many moons ago when I first got a track pump, realising that the old 'finger squeeze' is pointless. Since I'm just off the chart (it stops at 82kg), I'm roughly in the ballpark.

I've not had a pinch flat since that I can recall, and don't notice any comfort issue at current pressures.

Although, I haven't had 25's for a while, my guesstimate was probably a bit off for them, think I ran them more around 90PSI.

gmacz

I run 80psi for comfort and the mudguards last longer as well due to less vibrations.

northcliff66

I find this is perfect.

“Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33
Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33
Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33
Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33
Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67
Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67

Front Pressure = .9*Rear Pressure

Drop by 5 psi if wet.

MattW267

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19744601#p19744601]northcliff66[/url] wrote:

I find this is perfect.

“Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33
Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33
Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33
Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33
Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67
Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67

Front Pressure = .9*Rear Pressure

Drop by 5 psi if wet.

Thanks northcliff66, tried out your method over the last month and it is spot on! Could have saved myself a lot of wasted time trying higher and lower combinations.

gubber12345

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19742825#p19742825]davidof[/url] wrote:

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19740924#p19740924]orangebox82[/url] wrote:

Hello all,

I always assume that if the tire has more air, it means that it is going to be light!

Don't pump over 150 psi or your wheels might float away!

rumbataz

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19744601#p19744601]northcliff66[/url] wrote:

I find this is perfect.

“Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33
Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33
Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33
Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33
Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67
Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67

Front Pressure = .9*Rear Pressure

Drop by 5 psi if wet.

Is the calculation for the front or rear tyre?

morgan_blake

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19744601#p19744601]northcliff66[/url] wrote:

I find this is perfect.

“Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33
Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33
Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33
Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33
Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67
Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67

Front Pressure = .9*Rear Pressure

Drop by 5 psi if wet.

How do you get the PSI so accurate. THe need on my toppeak one seems to move ever so slightly after I have pumped the tyre. Then i remove the nozzle, and sometimes a fair amount of air comes out.

cadseen

Pump the tyres up with Helium

Think the quality of the tyre itself will make more of a diferrence than tweaking the pressure.

k-dog

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19755575#p19755575]morgan_blake[/url] wrote:

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19744601#p19744601]northcliff66[/url] wrote:

I find this is perfect.

“Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33
Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33
Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33
Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33
Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67
Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67

Front Pressure = .9*Rear Pressure

Drop by 5 psi if wet.

How do you get the PSI so accurate. THe need on my toppeak one seems to move ever so slightly after I have pumped the tyre. Then i remove the nozzle, and sometimes a fair amount of air comes out.

You'll never get it that accurate - and that doesn't really matter. A decent pump should get you within 5 - better than that needs a separate gauge.

That noise you're hearing isn't air getting out of the tyre - when you release the pump the valve closes very quickly - but the pump and hose are at the same pressure as the tyre so when you release the pump the pressure goes back to normal so the noise you hear is that air escaping, not air from the tyre.

moscowflyer

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19742895#p19742895]mfin[/url] wrote:

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19741207#p19741207]doug5_10[/url] wrote:

Google 'road tyre pressure chart', Michelin one usually comes up most often.
Rider weight probably biggest influencing factor, 25c's shouldn't need much more than 100PSI unless you're nearing 90 - 100 kg. That is the benefit of larger tyres, they can run at lower pressures, improving comfort. For instance I'm 83kg, run 23c at 105-115 and 25c at 95-105.
Pressures too low will invite snake bite punctures.
Pressures too high will give harsh ride, and you will only roll faster on the smoothest of smooth roads. i.e. a velodrome

You are running pressures too high for your weight.

I've always had a fear of pinch flats so have without fail always ridden both my 23 front and 25 rear GP4000s at 120. Looks like I need to drop it by 15-20.

Bobbinogs

Yeah go for it and see how you get on. I am currently running somewhere around 70F/80R on 25s with my weight around 65kg. Sometimes I go up a bit at the front for hilly courses but, ultimately, if you twonk a large pothole head on it doesn't really matter what pressure you are running at. On a club run we hit a really bad section of road with potholes galore and many suffered from snakebites...and tyre pressures didn't seem to come into it, just a case of who hit the holes.

I personally think anything below 70 is chancing it a bit from snakebike/tyre bead-rim adherence but that is just me.

wbrad

As a newb not so long ago, I used to think the tighter the tire, the less rolling resistance so always kept my tires at 120psi. A bit of reading taught me this is not the case so I dropped my pressures to around 95 rear and 85 front. I instantly picked up at least 1kmph average speed and a more comfortable ride to boot. Sometimes pressures get below 70 before I remember to check them and I feel the bike getting noticeably sluggish.
Oh, and I think putting more air in your tires will actually make them very slightly heavier (but not enough to make any real difference), not lighter.
I'm 70kg and run 23mm Conti 4000sII.

alwayscycle

Yes I was the same. Ran tyre pressure far to high as a newbie and the bike bounced and the lack of control negatively impacted my rides. I'm about 75kg and run Conti 4000sII at 95psi on the back and 85 at the front. This made a massive difference to ride quality, control and as a result speed.

Magem

My rule of thumb
- wet commute 70-80
- fast & dry weekend rides 90-105