Work out tyre pressure adjustment instantly with clear inputs, formula shown and shareable results.
Tyre pressure falls about 0.01 bar (0.15 psi) per degree Celsius of temperature drop, so a 12 degree cold snap costs over a tenth of a bar. Extra load needs extra pressure, which is why door-jamb placards list a separate laden figure.
Pressure adjustment
pressure change = -0.0096 bar per degree C; load increase adds roughly proportionally
Cold, before driving. A warm tyre reads 0.2-0.3 bar higher, and letting that out leaves it underinflated when cool.
Fuel economy falls 1-2% for every 0.1 bar low, tyre shoulders wear rapidly, and heat build-up raises the risk of a blowout.