Tire Pressure Adjustment by Temperature

Tire PSI changes ~1 psi per 10°F. Adjust for outdoor temp delta from setting temp.

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How to use this calculator

  • Enter current PSI + temp.
  • Enter target temp.
  • Adjust PSI if needed.

About this calculator

Tire pressure obeys Gay-Lussac's law: at constant volume, pressure varies with absolute temperature. Practical rule: ~1 psi per 10°F. Inflating to 32 psi on a 70°F summer day → 28 psi on a 30°F winter morning. Always set pressure to the door-jamb spec at "cold" temperature (sitting overnight in same temp as ambient). Driving heats tires +10-15°F → +1-2 psi. Severely under-inflated tires (>5 psi low) wear faster, run hotter, and waste fuel.

Frequently asked

When to check?+
Cold (parked overnight) at start of a temp-change season — fall and spring. Set to door-jamb spec.
Daily fluctuation?+
Cold morning to hot afternoon: 5-10°F → 0.5-1 psi up. Driving adds another 1-3 psi. Both normal.
TPMS triggers?+
TPMS warning typically at 25% under spec. With ambient drop of 30°F: 32 psi → 29 psi → ~9% drop = no warning yet, but check.
Nitrogen vs. air?+
Nitrogen leaks slightly slower (bigger molecule), but temp-pressure law is the same. Nitrogen marketing oversold; air is fine.
Why does cold matter?+
Door-jamb spec is "cold" — measured before driving. Hot tires read 3-5 psi higher. Adjusting to spec while hot = under-inflated when cold.

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