tirepressure

Tire pressure is the amount of air pressure inside a vehicle's tires. It is usually measured in psi (pounds per square inch) in the United States or kilopascals (kPa) elsewhere. The recommended tire pressure for a vehicle is specified by the manufacturer and can be found on the tire information placard on the door jamb, in the owner's manual, or sometimes inside the fuel filler door. The value is for cold tires and reflects the load the vehicle is designed to carry under normal driving conditions. Common passenger car pressures are often in the 30 to 35 psi range.

To measure pressure, use a tire pressure gauge and check when tires are cold. Remove the valve cap, place the gauge on the valve stem, and read the pressure. Compare to the recommended figure; adjust by adding or releasing air as needed. Do not rely on readings from hot tires, since driving heats the air and raises the measured pressure.

Effects of improper inflation: Underinflation can cause increased rolling resistance, higher fuel consumption, uneven wear on the tire shoulders, and a greater risk of heat buildup that can lead to tire failure. Overinflation can cause excessive center-tread wear, a harsher ride, and reduced traction in certain conditions. Both conditions can impair handling and braking.

Maintenance practices: Check tire pressure at least monthly and before long trips, especially when carrying heavy loads or in extreme temperatures. Use a reliable gauge and ensure tires are cold before measuring. Also check the spare tire if present, and keep seasonal tires inflated to the correct pressure. If the vehicle is equipped with a Tire Pressure Monitoring System (TPMS), heed its warnings and service guidance.