We spoke to Gary Powell, Technical Manager at Bridgestone Tyres. He says: "All cars have pressure recommendations within their driver handbook, door pillar or petrol flap. These recommendations are generally for load condition and speed (e.g. normal running, high speed running, etc…).

All tyre pressures should be checked in cold condition, under normal ambient conditions. Pressures should never be adjusted when tyres are in hot condition, as the pressure recommendations are set by the Original Equipment Manufacturer (OEM) in cold conditions.

Obviously when in running condition then air pressure within the tyre will increase due to heat conduction, heat radiation, kinetic and frictional forces. However, if you experience any vehicle or steering vibration or a change in tyre noise (such as a continual noise increase regardless of road surface), then you should reduce your speed and pull over at the safest opportunity, so that you can inspect the tyre(s) fully for damage. If unsure, always seek professional guidance from a fully trained tyre technician."