Tyre Pressure Calculator
Ideal gas law + humidity correction
Hot Conditions (on track)
Measure tyre air temperature and pressure immediately after coming off the circuit, before the tyre cools.
Measure air temp inside tyre, not surface temp
Typical circuit range: 170–220 kPa (gauge)
—
Derived from cold RH · Psat(cold) / Psat(hot) — sealed tyre assumption
Cold Conditions (pre-session)
Measure actual tyre air temperature before the session — not just ambient. Tyres in sunlight or a warm garage will be warmer than ambient.
Results
⚠️ Check inputs — temperatures must be realistic and pressure must be positive.
Required cold tyre pressure
—kPa (gauge)
—
bar
—
psi
Intermediate values ▶ show
Humidity correction effect
—kPa
Formulas ▶ show
💡 Hot humidity is calculated automatically from the cold RH and the temperature rise, assuming the tyre is sealed (fixed absolute moisture content). As temperature rises, saturation pressure increases sharply, so relative humidity drops significantly — e.g. 60% RH at 20°C becomes roughly 5–8% at 80°C. When using nitrogen, RH is 0% on both sides.