How to Check a Tire's Air Pressure
Buy a good air-pressure gauge. That may seem obvious, but it’s crucial. You won’t get an accurate reading from an air-pressure gauge at a gas station, and an accurate measurement is pivotal, because underinflated tires handle poorly on the road, says Andrew Vinciquerra, who owns A.V.A. Performance Inc., an auto-repair shop in Long Island City, New York, and specializes in prepping his customers’ cars for road trips. Because low tires spin with more difficulty, they require more energy from the engine and so waste gas. “Purchase a gauge that doesn’t run on batteries and you won’t need to worry that they’ll die,” Vinciquerra recommends.
Determine the ideal pressure. Says Vinciquerra, your car manual will tell you where to locate a sticker―usually on the doorjamb on the driver’s side―that indicates your tires’ maximum pressure, which is how much weight they can support. One tire at a time, unscrew the tire cap and place the gauge over the valve fitting. Press in for one second and listen for the hissing sound of escaping air. The gauge will lock the reading into place so you can see it clearly. If the number is too low, add air to the tire for 30 seconds, then test again. Repeat until the pressure is correct. Be sure to check the spare tire’s pressure as well.