Having properly inflated tires not only keeps you safe, but it enhances the performance of your vehicle.
Check the air pressure in your tires, including the spare, at least once a month and before extended driving. Tires should be checked when they are cold - do not reduce pressure when the tires are hot. Use an air pressure gauge to check pressre and maintain it according to the recommened level in your vehicle owner's manual or on the vehicle's tire placard.
Over-inflation can cause the tire to be more susceptible to damage. Additionally, over- and under-inflation can affect the vehicle's handling. Cold tire pressures should never be higher than the limit molded on the sidewall of the tire.