COLD PSI

Cold tire pressure, explained.

Estimate how temperature may change a gauge reading—then follow a safer real-world check.

Cold means undriven for at least 3 hours—not freezing weather.

Estimate the reading

Pressure unit
Temperature unit

Use the placard pressure for the tire being checked. Front and rear values may differ.

The ambient temperature when this tire was cold and set to the placard pressure above.

The ambient temperature you want to estimate.

Driving state

Choose “Parked 3+ hours” for a cold reading.

Estimated gauge reading

30.8 PSI

4.2 psi lower

70°F / 35 psi 25°F / 30.8 psi Temperature
Illustrative comparison; not to scale.

What to do next

Check with a gauge before driving. Adjust the measured pressure to the vehicle placard value: 35 psi.

An estimate is not a leak test.

If one tire is visibly damaged, much lower than the others, or keeps losing pressure, stop relying on the estimate and have it inspected.

Use the estimate safely

  1. 1

    Find the placard

    Locate the recommended pressure on the driver-side door placard or in the owner’s manual.

  2. 2

    Measure cold

    Use a gauge after the vehicle has been parked for at least 3 hours and before a long drive.

  3. 3

    Check each tire

    Check all tires and the spare, if fitted. Use each tire’s specified pressure; the spare may differ.

Compare temperature scenarios

The same starting pressure at several comparison temperatures. These are model estimates after temperature equilibrium, not measured readings or inflation targets.

Comparison temperatureEstimated readingChange from start

Planning a warm-garage check? Record actual gauge readings separately.

Method

The estimate uses the ideal-gas relationship on absolute pressure and absolute temperature:

(P2 + atmosphere) = (P1 + atmosphere) × T2 ÷ T1

P is gauge pressure. “Atmosphere” is 14.6959 psi or 101.325 kPa. Temperatures are converted to kelvin. This assumes the tire started at the entered placard pressure, fixed volume, no air loss and constant standard atmospheric pressure.

Both temperatures represent the air inside a rested tire after it has reached ambient temperature. Sun, driving heat, altitude changes and leaks can make a real reading differ. This is a temperature-only model, not a measured reading or an inflation target.

Sources

  • NHTSA TireWiseplacard pressure, cold-tire definition and gauge checks
  • Transport Canadacold-weather pressure guidance and rule of thumb
  • NISTstandard atmosphere and pressure unit conversions
  • NASA Glennideal-gas relationship and absolute temperature

Sources checked November 5, 2026. Your owner’s manual controls for your vehicle.

FAQ

What does cold tire pressure mean?

It means the tire has not been warmed by driving. NHTSA defines a cold tire as one that has not been driven for at least three hours. It does not mean a specific outdoor temperature.

Can cold weather turn on the TPMS light?

Yes, a temperature drop can lower the gauge reading enough to trigger a warning. A warning can also involve a leak or another problem, so check every tire with a gauge instead of assuming the weather is the only cause.

Should I use the number on the tire sidewall?

No. The sidewall number is a maximum for the tire, not the vehicle’s recommended pressure. Use the driver-side door placard or owner’s manual.

Should I let air out after driving?

Do not bleed a warm tire down to the cold placard value. Recheck after the vehicle has been parked for at least three hours and adjust from that reading.