Cold inflation pressure is the inflation pressure of tires before the car is driven and the tires warmed up. Recommended cold inflation pressure is displayed on the owner’s manual and on the placard (or sticker) attached to the vehicle door edge, pillar, glovebox door or fuel filler flap. Drivers are encouraged to make sure their tires are adequately inflated, as suboptimal tire pressure can greatly reduce fuel economy, increase emissions, increased wear on the edges of the tire surface, and can lead to premature failure of the tire. Excessive pressure, on the other hand, will lead to blowouts, decrease braking performance, and cause uneven wear (i.e. greater wear on the inner part of the tire 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. Ambient temperature affects the cold tire pressure. Cold tire pressure varies directly with the absolute temperature, measured in kelvins. The following table shows the relationship between ambient temperature and cold tire pressure, where the volume of air in the tire remains constant.