Cold inflation pressure

Cold inflation pressure is the inflation pressure of tires as measured before a car is driven and the tires (tyres) warmed up. Recommended cold inflation pressure is displayed in the owner's manual and on the Tire Information Placard attached to the vehicle door edge, pillar, glovebox door or fuel filler flap.

Cold inflation pressure is a gauge pressure and not an absolute pressure.

This article focuses on cold inflation pressures for passenger vehicles and trucks. The general principles are, of course, applicable to bicycle tires, tractor tires, and any other kind of tire with an inernal structure that gives it a defined size and shape (as opposed to something that might resemble a very flexible balloon).

A 2001 NHTSA study found that 40% of passenger cars have at least one tire under-inflated by 0.4 bars (6 psi) or more.^[1] The number one cause of tire failure was determined to be under-inflation. Drivers are encouraged to make sure their tires are adequately inflated at all times.

Under-inflated tires can greatly reduce fuel economy, increase emissions, cause increased wear on the edges of the tread surface, and can lead to overheating and premature failure of the tire.

Excessive pressure, on the other hand, will lead to impact-breaks, decreased braking performance, and increased wear on the center part of the tread surface.

Tire pressure is commonly measured in psi in the imperial and US customary systems, bar, which is deprecated but accepted for use with SI, or the kilopascal (kPa), which is an SI unit.