Cold tire pressure in summer still means rested.
In this guide, “cold” follows NHTSA’s three-hour, not-driven condition; it does not require freezing weather. A rested tire on a summer morning can be checked against its applicable cold specification. A winter tire heated by driving is a warm reading.
Direct sun and recent driving can change the reading conditions. Record those conditions rather than assuming that every higher number means overinflation. Michelin’s inflation guidance cautions against releasing air from a warm tire. A summer tire type and a cold-pressure measurement are different concepts.
Should you add air when the weather gets colder?
Transport Canada explains that cooling lowers tire pressure. Take an actual gauge reading and compare it with the specification for that tire, load and measurement condition. Follow the vehicle’s inflation instructions when a cold reading is low; do not deliberately leave it low just because warmer weather is forecast.
If TPMS comes on, inspect and check the tires rather than assuming weather is the only cause. Use the warning-pattern guide. Visible damage, serious underinflation or repeated loss requires appropriate assistance; a temperature calculation does not clear a tire for driving.
What if you add air in winter and the weather warms?
With the amount of air unchanged, a temperature rise can increase the reading. The useful response is another actual cold check under the new conditions, compared with the vehicle’s applicable specification. Follow its adjustment procedure if that cold measurement is outside the specified value. Do not bleed down a recently driven tire to a cold target.
For illustration only, start at 35 psi and 45°F, then allow the tire air to reach 70°F. With no air loss, fixed volume and standard atmospheric pressure, the ideal-gas model gives 37.5 psi. This is a model-based estimate, not a new inflation target or a measurement of your tire.
How much pressure changes with temperature?
Transport Canada gives an approximate decrease of 7 kPa, or about 1 psi, per 5°C temperature drop. Its page is dated December 10, 2013. Treat this as a rough scale, not a precision conversion for every tire or starting pressure.
The five-row temperature table instead uses the entered starting pressure and the stated model assumptions. Neither the rule of thumb nor the model accounts for a leak, driving heat or a tire that has not reached the assumed temperature. A vehicle PSI chart still requires the correct vehicle data.
Keep the recheck tied to the vehicle.
Keep the placard values, date, actual readings and conditions together in the four-wheel check sheet. It accepts separate front, rear and spare values; warm or unknown readings are recorded without a cold-pressure deficit.
Check at least monthly and before a long trip, as Michelin recommends, and follow any more specific vehicle instructions. Extra checks after a substantial weather change help establish the current readings; they do not replace the regular schedule. If a change repeats or a tire behaves differently, obtain an assessment rather than attributing it to weather alone.
Sources & scope
- NHTSA TireWise
U.S. guidance: cold readings, vehicle placards, monthly checks and TPMS warning patterns.
- Transport Canada
Individual front, rear and spare specifications; temperature-related pressure changes. Page modified December 10, 2013.
- Michelin tire-inflation guide
Warm-tire cautions, gauge checks and inflation steps. Updated July 20, 2026.
- NASA Glenn: ideal-gas equation
Ideal-gas relationship and absolute temperature; supports the model, not tire-specific validation.
Primary sources checked November 5, 2026. This is not a vehicle-specific inspection.