Tire Pressure Temperature Calculator
See how temperature shifts your tire pressure.
Positive if warmer, negative if colder than when you set the pressure.
Results update as you type.
How it works
Tyre pressure is not a fixed number; it drifts with the weather because the air inside expands when warm and contracts when cold, and this tire pressure temperature calculator estimates how much. Enter your current pressure and the temperature change since you set it, positive for warmer and negative for colder, and the tool returns the adjusted pressure and the size of the shift. This matters more than most drivers realise. A cold snap can drop your tyres several psi below the recommended figure, triggering the dashboard warning light, increasing rolling resistance and fuel use, and hurting grip and tyre life. A hot day or a long, fast drive does the opposite, raising pressure above the target. Because the effect is predictable, you can anticipate it: set pressures with the season in mind, and understand why the light appears on the first frosty morning. The estimate rests on the well-known guideline of about one psi for every ten degrees Fahrenheit. It comes from the gas law that ties pressure to temperature in a sealed, roughly fixed volume. The rule is an approximation, not a laboratory-grade figure, but it is close enough to plan by and to sanity-check a warning light. Always set and check pressures when the tyres are cold, using your vehicle's recommended value, and treat this calculator as a guide to how the reading will move as conditions change.
adjusted psi = current psi + (temperature change ÷ 10)
Air inside a tyre behaves as a gas, so its pressure rises and falls with temperature at roughly constant volume. A widely used rule of thumb is that tyre pressure changes by about one pound per square inch for every ten degrees Fahrenheit of temperature change. Dividing the temperature change by ten estimates the pressure shift, which is added to your current pressure when it warms and subtracted when it cools, giving the expected new reading.
Source:Ideal gas law rule of thumb (~1 psi per 10°F)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter current pressure and temperature change.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Adjusted pressure updates instantly as you type — no button to press.
Frequently asked questions
Why does tire pressure change with temperature?
The air sealed inside a tyre follows the gas laws: at a roughly constant volume, its pressure rises as it warms and falls as it cools. When temperatures drop overnight or with the season, the air contracts and pressure reads lower; when the day heats up or the tyre warms from driving, pressure climbs. This is normal physics, not a leak, and it is why pressures should be checked when tyres are cold.
How much does pressure change per degree?
A common rule of thumb is about one pound per square inch for every ten degrees Fahrenheit of temperature change, or roughly one psi per five to six degrees Celsius. So a twenty-degree Fahrenheit swing shifts pressure by about two psi. This is an approximation that works well for typical car tyres near normal inflation, and it is accurate enough to anticipate warning lights and seasonal adjustments.
Should I set pressure cold or warm?
Always set and check tyre pressure when the tyres are cold, meaning before driving or after the car has sat for a few hours, because driving heats the tyres and temporarily raises the reading. The pressure printed on your door jamb refers to cold pressure. If you must check warm tyres, expect them to read a few psi higher than the cold target, and do not bleed air to compensate.
Why does my low-pressure warning appear on cold mornings?
As temperatures fall overnight, the air in your tyres contracts and pressure can drop several psi, enough to trip the tyre-pressure monitoring system. This is why the warning light so often appears on the first cold morning of autumn. Usually the tyres are not damaged; they simply need topping up to the recommended cold pressure. If the light persists after inflating, have the tyres checked for a slow leak.
Is the one-psi-per-ten-degrees rule exact?
No, it is a practical approximation rather than a precise law. The exact change depends on the starting pressure, the tyre's volume, and altitude, and it follows from the ideal gas relationship between pressure and absolute temperature. For everyday car tyres at normal inflation the rule is close enough to plan seasonal adjustments and to make sense of a warning light. For critical applications, measure directly with an accurate gauge.