Free tool

Hot / cold tire pressure calculator

Tire pressure rises as the air inside heats up. Enter your cold pressure and temperatures to predict the hot pressure, or enter the hot pressure you want and get the cold pressure to set before you go out.

Hot air temperature inside the tire is usually below the tread surface temperature. If you only have tread temps, start with a value a little below them and refine with a gauge.

Predicted hot pressure
37.8psi
Rise
7.8psi
Temperature ratio
1.174
Absolute ref.
14.7psi

Dry air, sealed tire, ideal gas law. Moisture and carcass stretch change the real rise, so always confirm with a gauge.

How it works

  1. 1Air in a sealed tire follows the gas law: absolute pressure rises in proportion to absolute temperature.
  2. 2Absolute pressure = gauge pressure + atmospheric pressure (about 14.7 psi at sea level).
  3. 3Real tires stretch a little as they heat, and moisture in the air adds more rise, so treat the result as a starting point and check with a gauge after each session.

FAQ

Why do my pressures rise more than the calculator says?

Moisture in compressed shop air expands more than dry air. Many track drivers fill with nitrogen or dry air for more predictable rise.

Should I let air out between sessions?

Only to set your hot target while the tires are hot. If you bleed hot tires to a cold number, they’ll be underinflated when they cool and heat up again.