The first thing to check, and something that should be checked most often, is the tire pressure. Every car has an information plate, usually inside the driver's door, which shows the manufacturer's recommended tire pressures for that vehicle. While many tires do have a pressure figure listed on the sidewall, this is the maximum pressure the tire is designed to withstand, not the recommended inflation level. Always take the inflation figures from the car, not from the tires.
The following table shows some of the problems that can result from incorrect tire inflation.
Reduced gas mileage
Tire failure due to additional stress on sidewalls
Reduced handling due to tires flexing
Increased tread wear
Harsher ride and increased stress on suspension
Increased chance of blowout
Checking the tire pressure regularly and keeping it at the proper level can not only extend the life of the tire but also increase road safety.