Tire Pressure and Temperature Calculator
Enter the pressure you set and the temperatures to see the new tire pressure.
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Tire Pressure and Temperature Calculator by TheCalcTools
How the Tire Pressure and Temperature Calculator works
Gas pressure changes with absolute temperature. The calculator uses absolute pressure (gauge plus 14.696 psi) and absolute temperature.
Enter the pressure you set, the temperature then and the temperature now.
The result shows the new gauge pressure and what to fill to if you want the original pressure back.
The formula
Worked example
Using the default values shown in the calculator:
| Pressure when set (psi) | 35 |
|---|---|
| Temperature when set | 70 |
| Temperature now | 20 |
| Temperature unit | Fahrenheit |
- 35 psi set at 70 °F, now 20 °F: the new pressure is 30.3 psi, a change of -4.7 psi.
- In metric that is 209 kPa or 2.09 bar.
Result:
| Pressure now (psi) | 30.3 |
|---|---|
| Change (psi) | -4.7 |
| Pressure now (kPa) | 209 |
| Pressure now (bar) | 2.09 |
| Fill to this in the new temperature to match your set pressure (psi) | 40.2 |
Frequently asked questions
How much does tire pressure drop in cold weather?
About 1 psi for every 10 °F (5.5 °C) drop in temperature.
When should I check tire pressure?
When the tires are cold, before driving, and use the pressure on the door placard rather than the number on the tire sidewall.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.