Tire Pressure Temperature Calculator
Enter your starting tire pressure and the starting and final temperatures to see the new pressure. Pressure rises in heat and falls in cold by roughly one psi per ten degrees Fahrenheit.
How to adjust tire pressure for temperature
- Enter your current (cold) tire pressure in psi.
- Enter the temperature when you set it and the new temperature in Fahrenheit.
- Read the new pressure and the change in psi.
Examples
Cold snap from 70 F to 30 F
32 psi set at 70 F, now 30 F
about 28.47 psi, a drop of 3.53 psi
Rule of thumb
every 10 F change
about 1 psi change
Frequently asked questions
How much does tire pressure change with temperature?
Roughly one psi for every ten degrees Fahrenheit. Pressure falls as it gets colder and rises as it gets warmer, following Gay-Lussac's gas law.
Why does the calculator use absolute temperature and pressure?
Gas laws work on absolute scales. Temperatures are converted to Rankine by adding 459.67, and gauge psi is converted to absolute by adding 14.7, then the result is converted back.
Should I add air when it gets cold?
If pressure drops below the recommended cold value, top it up. Set pressures when the tires are cold for the most accurate reading.
Does driving change the reading?
Yes. Driving heats the tires and raises pressure, which is why you should check and set pressures before driving, when the tires are cold.
What is the exact formula?
Final absolute pressure equals initial absolute pressure times final absolute temperature divided by initial absolute temperature. Subtract 14.7 to return to gauge psi.
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