There's been debate here and there about overinflating and underinflating tires... And how it's common to overinflate in order to "save gas" etc.

To further complicate the matter, the specified psi for your car tires assume that the tires are COLD and still undriven for the day.

So how do you adjust for heat generated from 1) outside air temperature, and 2) heat generated from driving if your nearest airpump gas station is a mile or two away?

This article seems to suggest the following:

1) If you have to drive a bit to get to your nearest airpump/station, you should increase your psi by 1 psi for every 5 min. of driving; but no more increases after 20 min. of driving.

2) You should likewise increase your psi by 2 to 5 psi if you pump air while the weather is very hot... because your tire's psi will drop by 2 to 5 psi the next morning when it's cold and undriven.

So does this mean that you should "overinflate" tires by up to 9 psi if you load when it's very hot and you've been driving for more than 20 min.?

http://www.tirerack.com/tires/tiretech/tec...e.jsp?techid=73

I suggest you inflate your tires by nitrogen.

Then you will cut all the overinflating and underinflating problem .

The tire pressures given by most manufacturers are split between standard use and heavy load/high speed use. Tires will NOT be warm after 5 minutes of driving. Even on a racetrack it takes 2 laps to get heat into the tires so trundling to your nearest gas station will definitively not do that.

The beauty of it all is the simplicity, you put the right cold pressure ( cold tire as in NOT a hot tire from long drive, no relation to the outside weather) and during long drives the tire will increase its pressure automatically due to the generated heat. The increase in pressure will probably be limited to around 3 to 5 psi. No issue there. If you use Nitrogen, the pressure increase will be less and the loss of air will be less so Nitro is a safer solution.

H

The tire pressures given by most manufacturers are split between standard use and heavy load/high speed use. Tires will NOT be warm after 5 minutes of driving. Even on a racetrack it takes 2 laps to get heat into the tires so trundling to your nearest gas station will definitively not do that.

The beauty of it all is the simplicity, you put the right cold pressure ( cold tire as in NOT a hot tire from long drive, no relation to the outside weather) and during long drives the tire will increase its pressure automatically due to the generated heat. The increase in pressure will probably be limited to around 3 to 5 psi. No issue there. If you use Nitrogen, the pressure increase will be less and the loss of air will be less so Nitro is a safer solution.

H

You make logical sense, Hak.

But could TireRack be wrong about their study, then?

You talk about small psi corrections, hope you people check your gauges I find most are wildly out some more than 10psi

On you way home stop at the petrol station and overinflate the tyres by 2 psi.

Next morning before you drive the car check the tyre pressure when the tyres are cold.

Back in my bike racing days, we used the 10 % rule. If cold pressure was 30-lbs, hot was 33-lbs. Adjust accordingly - good for 150 + mph