Tire Pressure Formula
01-10-13, 08:56 AM
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Tire Pressure Formula
O.K. So maximum pressure is listed as 120 psi. In mountain biking there is a generally accepted starting point regarding tire pressure. The formula is body weight in pounds/7
as a good starting point. 200 pound rider= 28-29 psi and 260 pound rider =37 psi.
Now road is a whole different animal and I imagine pinch flats are not as common on a road (smooth road anyway).
So where does one start with tire pressure 90, 100, 110 or is there a similar formula for the road??
as a good starting point. 200 pound rider= 28-29 psi and 260 pound rider =37 psi.
Now road is a whole different animal and I imagine pinch flats are not as common on a road (smooth road anyway).
So where does one start with tire pressure 90, 100, 110 or is there a similar formula for the road??
01-10-13, 09:00 AM
#2
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There are calculators online. But it also depends on your specific tire and rim widths. I like riding at lower PSI, and have found that with Continental 23mm tires on 23mm rims (a little wider than normal) I can go at 85f/100r without getting pinch flats on the roads I ride and I weigh around 180lbs.
For most people of average weight riding typical 23mm tires and standard clincher aluminum road rims of around 19mm something around 100f and 110r is a good starting point.
Pinch flats can be very common on the road because their just isn't much space between the rim and the road and even at high pressure there just isn't that much air in your tires. Being just a little low or having a slow leak on a long ride will cause problems.
For most people of average weight riding typical 23mm tires and standard clincher aluminum road rims of around 19mm something around 100f and 110r is a good starting point.
Pinch flats can be very common on the road because their just isn't much space between the rim and the road and even at high pressure there just isn't that much air in your tires. Being just a little low or having a slow leak on a long ride will cause problems.
Last edited by canam73; 01-10-13 at 09:05 AM.
01-10-13, 09:08 AM
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Relax. Pump it up to 100 and then next time more or less depending on how you like the ride.
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01-10-13, 09:29 AM
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Charts are a place to start. However, IMHO, most of them can give results that vary substantially from what people are doing sucessfully in practice.
Appropriate tire pressure depends in part on how you ride. Some people ride "heavier" and are more prone to pinch flats than others.
So what do you weigh, and what size tires are you riding?
Appropriate tire pressure depends in part on how you ride. Some people ride "heavier" and are more prone to pinch flats than others.
So what do you weigh, and what size tires are you riding?
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01-10-13, 10:15 AM
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There's this one https://www.dorkypantsr.us/bike-tire-...alculator.html Not advocating it myself.
01-10-13, 10:58 AM
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Michelin has a recommended tire pressure chart based on tire size and rider weight. Check their web site.
01-10-13, 01:58 PM
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I have developed this top secret propriatary formula that I am now ready to share with the world:
Front wheel: Take your weight and divide by 2, add 100, and subtract 1/2 your weight.
Rear: Take your weight, multiply by 2, add 110, then subtract double your weight.
Front wheel: Take your weight and divide by 2, add 100, and subtract 1/2 your weight.
Rear: Take your weight, multiply by 2, add 110, then subtract double your weight.
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01-10-13, 02:32 PM
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01-10-13, 04:23 PM
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I think I am doing it wrong... I can't get any number but 100 in the front and 110 in the... wait a minute!!... you sneeky sneekers.
01-10-13, 04:26 PM
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01-10-13, 06:49 PM
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01-10-13, 07:28 PM
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Here's a chart that is pretty well circulated which may help :
Calculate Rear tire pressure:
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
Calculate Rear tire pressure:
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
01-10-13, 07:39 PM
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01-10-13, 08:35 PM
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Here's a chart that is pretty well circulated which may help :
Calculate Rear tire pressure:
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
Calculate Rear tire pressure:
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
Have a nice life
01-10-13, 08:49 PM
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You could always try N+1.
Last edited by timmy29er; 01-11-13 at 12:16 AM.
01-10-13, 08:52 PM
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Here's a chart that is pretty well circulated which may help :
Calculate Rear tire pressure:
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
Calculate Rear tire pressure:
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
01-10-13, 08:58 PM
#20
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I rode in to work this week with only 40 psi in my tires. I pumped the rear today to 90 psi. I only weigh 150 lbs. Tires are 700 x 28. Haven't yet had a pinch flat, touch wood!
01-10-13, 10:15 PM
#22
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Here's the formula I have developed after years of research:-
[1] Think of a number.
[2] Double the number.
[3] Add 187.
[4] Divide by 2.
[5] Take away the number your first started with.
[6] Your answer is the tire pressure.
[1] Think of a number.
[2] Double the number.
[3] Add 187.
[4] Divide by 2.
[5] Take away the number your first started with.
[6] Your answer is the tire pressure.
01-11-13, 12:58 AM
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ask Tom Bonnen about his Paris-Roubaix tire pressure.
In all honesty, you gotta figure that out yourself. If the ride is too rough @ 120psi (bouncy, wrists hurt), then you have the tire pressure too high.
Right now I've lowered my tire pressure because of the debris/snow outside. I want more traction and I reduced 10psi which is just about right. No way i'm going as fast(err,slow) as I was during the summer.
In all honesty, you gotta figure that out yourself. If the ride is too rough @ 120psi (bouncy, wrists hurt), then you have the tire pressure too high.
Right now I've lowered my tire pressure because of the debris/snow outside. I want more traction and I reduced 10psi which is just about right. No way i'm going as fast(err,slow) as I was during the summer.
Last edited by Biscayne05; 01-11-13 at 01:03 AM.
01-11-13, 02:49 AM
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After working to catch up to a relatively fast cyclist on a path out this way... but then hitting a sidewalk style stretch that went on for about 100 yards/rough pavement after that - I got horribly dropped as I was bouncing all over the place and when I realized the err of my pressure ways I got bummed and that made me even more tired. That day I realized more pressure does not = better, pressure has to be right and IMO it varies with road surfaces as well as weight. I had both my tires @ 125 that day (the rear may have been higher even!)... and although it was horrific over ever road imperfection - once I hit fresh pavement my speeds shot up and my effort went way down.
I'm ~200 + a bookbag with anywhere from 5 to 15lbs of stuff in it so my riding weight is somewhere around 215 and 230. I've found ~115 rear and ~105 front to help keep things less bouncy and getting 10% or so below that feels too squishy and makes me fear a pinch flat.
I'm ~200 + a bookbag with anywhere from 5 to 15lbs of stuff in it so my riding weight is somewhere around 215 and 230. I've found ~115 rear and ~105 front to help keep things less bouncy and getting 10% or so below that feels too squishy and makes me fear a pinch flat.