How to Check Tire Pressure (Step by Step)

Open the driver's-side door and look at the door jamb - the metal frame that the door latches into. There's a sticker there with your car's recommended cold tire pressure printed on it, usually somewhere around 30 to 35 PSI for a regular sedan or SUV.

Use the number on this sticker, not the big number stamped on the side of the tire itself. The number on the tire is the maximum pressure the tire can hold, not what your car was designed to run at. The sticker is the right answer for your vehicle.

Crouch down by one of your tires and find the valve stem - that little black rubber nipple sticking out of the wheel with a screw-on cap. Twist the cap counter-clockwise to remove it, and tuck it somewhere you won't lose it. A shirt pocket works fine.

Check the four tires together rather than doing one at a time. That way you can read all four and decide which ones need air before you start the compressor or feed coins into the gas-station pump.

Take your tire gauge and press the open end straight down onto the valve stem. You'll hear a brief hiss of air as the gauge engages - that's normal, it's just a tiny puff. Push firmly enough that the hissing stops, which means the gauge has a good seal.

Keep it pressed on long enough to get a stable reading. If you can hear air leaking out the whole time, you're not pushing straight or hard enough. Pull off and try again.

Pull the gauge away and look at the reading. On a manual stick gauge the white plastic rod will stick out from the bottom with PSI numbers printed along it - read the highest number that's still showing above the lip.

Write the number down or remember it. You're going to compare it to the recommended PSI on the door-jamb sticker in the next step. Repeat the gauge press on each of the four tires before you move to filling.

Look back at the sticker on the driver's-side door jamb. The chart shows the recommended cold tire pressure for the front tires and the rear tires - they're usually the same number, but not always. Match each tire's gauge reading against the sticker's number.

If a tire is more than 2 PSI under the recommendation, it needs air. More than 2 PSI over, and you'll want to release a little. Cold-tire readings are the standard, so do this when the car has been parked a few hours and the tires haven't been heated by driving.

Hook the air compressor hose onto the valve stem the same way you used the gauge. Most portable compressors have a built-in gauge so you can watch the PSI climb as the tire fills. Stop when you hit the door-sticker number.

If a tire is over-inflated, press the small pin in the center of the valve with a fingernail or the back of the gauge to release a short burst of air. Re-check with the gauge, repeat until you're at the right PSI. Slow and steady is faster than overshooting and bleeding back down.

Screw the valve cap back on, snug but not cranked down. Move to the next tire and repeat - press the gauge, read the PSI, top up or release until you match the door sticker, replace the cap.

Once all four tires match and you drive a few miles, the dashboard low-tire light will turn itself off. If it stays on after a short drive with all four tires at the right PSI, you may have a slow leak in one tire and a shop visit is worth scheduling.