Correct tire pressure is critical to tire wear and vehicle handling. A tire with low pressure dramatically increases the rolling resistance (which decreases fuel economy) and causes the tire to wear faster (due to excess heat). Tire pressure is based on tire type, vehicle weight, and ride performance desired. Tire pressure is measured with a tire pressure gauge in pounds per square inch (psi) or kilopascals (kPa). To help maintain optimal tire pressure, high purity nitrogen (over 93%) can be used instead of air (which is 78% nitrogen, 21% oxygen, and 1% water vapor and other gases).
Tire Pressure Monitoring System (TPMS). A TPMS is used to alert the driver if any tire is significantly low on pressure. Vehicles that have a gross vehicle weight ratio of less than 10,000 pounds (4,536 kg) and manufactured on or after September 1st, 2007 are required by the NHTSA to have a TPMS.
Tire Placard. The tire placard identifies the recommended tire pressure. It should be on the driver’s side door or jamb.
Checking Tire Pressure. Use a quality air gauge to check the pressure in your tires, including the spare, at least once a month. Always check when tires are cold and before long trips.