How to Check and Add Air to Car Tiresby eHow Cars Editor
Keeping your tires at their recommended pressure will increase their life span, improve your car's gas mileage and give you a smoother ride.
Let the tires cool before checking their pressure (tires are more inflated when warm, less when cold).
Remove the cap from the valve on 1 tire.
Press a tire gauge hard onto the valve and note the reading. The sound of escaping air means you haven't inserted the gauge properly: it's either pressed on askew or you're pressing too lightly.
Add air to achieve recommended pressure, which is listed on a sticker on the driver's side doorjamb and in the car's manual. If you overfill, you can release air by pushing on the tiny metal stem in the center of the valve with a fingernail or the tip of a pen or pencil. If you need to guess, 32 psi (pounds per square inch) is a good rule of thumb for most passenger cars with standard tires.
Replace the valve cap.
Repeat with each tire, including the spare (the status of its pressure is often forgotten until it's needed, and then it's too late).
Check the tread depth. Recommended depth differs with types of tires. For a standard sedan tire, a penny pushed into the tread can give you a rough reading. If you can see any of Lincoln's head, it may be time to replace the tire. A $15 tread-depth gauge can give you a more accurate reading. There may also be wear indicators built into the tread; if they show, replace the tire.
Check for even wear (see "How to Interpret Your Car's Tire Wear.") If the treads on the outside or inside are particularly worn, you may need to rotate your tires or have your alignment checked.
- check The pressure you see on the tire's sidewall is the tire's maximum pressure - a number you don't want to achieve unless you're planning on carrying a very heavy load in your car.
- check A slow leak may be the result of a bad or leaky tire valve.
- check To ensure you're getting an accurate reading, invest in a good tire gauge (which should cost around $20).
- check Go ahead and use the recommended pressure stamped on the spare's sidewall to fill it. A smaller "temporary" spare requires about 60 psi.