What PSI on your road tires?

[scottcw2]

I used to run 100-110, but then got some some tires that were rated higher than 120. 120 is what I run now for less resistance and I don't pick up as much crap from the road, so I flat a lot less. The obvious trade-off is a little comfort. This is for pure paved road riding.

So what PSI is everyone else using for road tires?

[BumbleBeeDave]

. . . in my Open Corsa Evo-CX. Used to run 110, but have notched it up a bit.

What I can't figure out, though, is what effect cold has on te psi. If I pump 120 inside, then go out and ride when it's 40 outside, what does the cold drop it to? There must be a formula . . . :confused:

BBD

[rePhil]

In my Continentals

[Bud]

. . . in my Open Corsa Evo-CX. Used to run 110, but have notched it up a bit.

What I can't figure out, though, is what effect cold has on te psi. If I pump 120 inside, then go out and ride when it's 40 outside, what does the cold drop it to? There must be a formula . . . :confused:

BBD

There is. The Gay-Lussac law states the proportionality:

(P1/T1) = (P2/T2)

So as the temperature of the gas drops (from T1 to T2), the pressure also drops proportionally.

Your example of filling the tire inside (at say 20 C) and then riding when it's cold (at perhaps 5 C) is a bit more complicated than that, as the T of the air in the tires will be a bit greater than the air temp of 5 C due to tire-road friction, etc.

Example: Pump the tires up indoors at 120 psi = 8.17 atm, 68 degrees F = 293 K (since the above law is a proportionality, we don't have to make these conversions, but it's more fun!). Ride outside where the temp is 40 F = 278 K. Assuming that this is the temp of the air in our tires, then the new pressure would be 7.75 atm which equals 114 psi.

SO the difference is not too great, but is neither negligible. . .

[Fixed]

I used to run 100-110, but then got some some tires that were rated higher than 120. 120 is what I run now for less resistance and I don't pick up as much crap from the road, so I flat a lot less. The obvious trade-off is a little comfort. This is for pure paved road riding.

So what PSI is everyone else using for road tires?
bro make sure your rim can handle the high psi cheers

[BarryG]

PSI depends on tire size and rider weight. Without all 3 numbahs, don't mean sheet.

[BumbleBeeDave]

I knew someone around here would know! To me, though, six pounds difference does sound negligible. Not enough to worry about.

BBD

[marle]

I run 120 but will NOT run higher despite what Vredestein claims-- there are rim limits.

[Bud]

Yea, I guess the 6 psi difference in the example is pretty small. I wouldn't be concerned with it. It seems that some people are pretty concerned with exact pressures (ie- the merits of 105 psi vs 110 psi).

Also, my little example above did ignore things like rider weight (as Barry mentioned) which will change the volume of the tire (slightly) contributing to an increase in pressure. The Gay-Lussac relationship I stated does not account for that. To do so, we'd need to use the combined gas law

((P1V1)/T1))= ((P2V2)/T2)

or you could use the ideal gas law

PV=nrT

The science is interesting to me, but I just pump 'em up until they feel right. . .

[Sandy]

I used to use 145 psi in some tires and 120/125 in others. Then I started dropping the pressure and reached 120 rear and 115 front. I recently purchased for the first time 700x25 tires. Based on recommendations from Forum members, I have used 102 rear (max on the tires) and 92 front. I never thought that I would try such low psi.

I have found that the lower psi helps in all aspects of riding, even in speed. I rode today on a basically flat ride. At the times I sprinted , I found that the speed (for me) was excellent. I geniunely believe faster then with my previous 700X23 tires.


Airhead Sandy

[Dr. Doofus]

120

[dirtdigger88]

85 front

90 rear

jason

[saab2000]

7-8 Bar

[jerk]

the jerk has no idea. the gauge on the pump is broken. the tires are hard enough.

jerk

[Grant McLean]

85 front
90 rear

jason


my hero.

-g

[Frankwurst]

85 front

90 rear

jason

Perfect...and I'll bet i weigh more than the dirt man. :beer:

[Erik.Lazdins]

IMHO+ATMO/2

Tires will ride quite a bit harder when its cold out. I ease up on pressure even more when its 30F or colder.

At 20F and below I don't worry about tire pressure I just think warm thoughts.

[dirtdigger88]

Perfect...and I'll bet i weigh more than the dirt man. :beer:

Im 180- how bout you

oh and my tires are anywhere from 27c to 30c-

Jason

[FierteTi52]

I weigh 170lbs and run 100 rear and 95-100 in the front. Tires are Michelin Pro Race 700x 23 or Vittoria Open Corsa CX 700x23. I run 60 in my Panaracer Pasela 700x35
Jeff

[Tailwinds]

I weigh about 123 lbs., ride 23 mm Michelin Pro Race 2's (usually), and have been running 100 psi front and rear (down from 110 psi)... feels just as fast and is a little more comfortable.

[Peter P.]

Bodyweight-130lbs.

tires-23mm

Pressure- 90-95psi.

[NateM]

Body weight 145.Michelin Pro Race2 25's,F 85 R 85-90

[William]

BW: 250-260

PSI: 120-125

TS: 28c

TT: Does it matter?


William

[davids]

My weight: 155
My tires: Veloflex Black
My pressure: 100 psi