Calculate how tire pressure changes with ambient temperature using the ideal gas law.
The cold tire pressure measured at the initial baseline temperature. This is the gauge pressure above atmospheric pressure.
PSI
The ambient temperature when the tire pressure was initially set or measured. Typically your garage or shop temperature.
°F
The new ambient temperature you want to calculate the tire pressure for. Rising temp increases pressure; falling temp decreases it.
°F
Standard atmospheric pressure is 14.696 PSI at sea level. Adjust for high-altitude locations where atmospheric pressure is lower.
PSI
Results
New Tire Pressure (gauge)-PSI
Pressure Change-PSI
Percentage Change-%
Temperature Difference-°F
Approx. Rule of Thumb-PSI
References:
Based on Gay-Lussac's Law (ideal gas at constant volume): P1/T1 = P2/T2 where pressures are absolute and temperatures are in Rankine. The common rule of thumb is approximately 1 PSI change per 10°F change in temperature. Actual results vary based on tire volume changes and gas composition.