Air pressure refers to the amount of air inside the tire pressing outward on each square inch of tire; expressed in pounds per square inch (psi) or kiloPascals (kPa), the metric designation for air pressure (6.9 kPa = 1 psi).

The importance of making sure your tire pressure is correct is often underrated. Incorrect tire pressures can compromise the stability of a vehicle, its handling and braking and, in extreme cases, could contribute to an accident. When tire pressure is kept at proper levels, optimum vehicle braking, steering, handling and stability are realized.

Under-inflated tires are costing you money. According to the Society of Automotive Engineers, a tire with an inflation level just two psi below the optimum level measurably increases fuel consumption.

The practice of reading the sidewall of a tire to find the pressure is incorrect. The number listed does not take into account the specific vehicle it is mounted on. Vehicle model and weight are factors in determining what tire pressure is correct. Many vehicles have two seperate tire pressures; one pressure for the front tires and another pressure for the rear tires.

To find the correct tire pressure for your car or light truck, look on the vehicle's doorjambs. A sticker is usually located on the vehicle's 'B' pillar. Some manufacturers place tire pressure stickers inside gas filler doors. Pressures can also be found in the vehicle's owners manual.

Keep in mind that pressures specified are for the specific tire and wheel combinations listed on the sticker or in the owner's manual.