The Right Tire Pressure Starts at the Door

A cold morning can bring on a tire-pressure warning even when nothing has punctured the tread. Pressure changes with temperature, so a reading that looked fine in warmer weather may dip as the air cools. Before adding air, find the number the car was designed around.

Find the car’s number

Look for the tire-information placard on the driver’s door jamb, or check the owner’s manual if it is not there. It lists the recommended pressure for the vehicle, sometimes with different settings for front and rear tires. The number molded into a tire’s sidewall is its maximum pressure, not a substitute for the carmaker’s recommendation.

Check pressure before driving, while the tires are still cool, and use a reliable gauge rather than judging by appearance. A tire can look normal while it is underinflated. If you have driven far enough to warm the tires, wait until they cool before treating the reading as a cold-pressure measurement.

Read the warning in context

A tire-pressure monitoring system is useful, but its warning light does not tell you which tire needs attention or how much air to add. Check all four tires with a gauge, then inflate them to the placard’s cold-pressure setting. If the light comes back after the pressures are corrected, or one tire keeps losing air, look for a leak or have the tire inspected.

Make it a quick habit

Pressure checks take little time when they are part of a monthly walk-around or a routine before a long drive. Keep a gauge in the glove box, and give the tires a look for cuts, bulges, or objects lodged in the tread. The door placard gives you the right starting point; the gauge tells you what is happening today.