BROWSE HOW TOs

How to Check and Add Air to Car Tires

By eHow Cars Editor

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Keeping your tires at their recommended pressure will increase their life span, improve your car's gas mileage and give you a smoother ride.

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Instructions

Difficulty: Easy

Things You’ll Need:

Step1

Let the tires cool before checking their pressure (tires are more inflated when warm, less when cold).

Step2

Remove the cap from the valve on 1 tire.

Step3

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.

Step4

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.

Step5

Replace the valve cap.

Step6

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).

Step7

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.

Step8

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.

Tips & Warnings

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.
A slow leak may be the result of a bad or leaky tire valve.
To ensure you're getting an accurate reading, invest in a good tire gauge (which should cost around $20).
Go ahead and use the recommended pressure stamped on the spare's sidewall to fill it. A smaller "temporary" spare requires about 60 psi.

Comments

Anonymous said

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on 8/23/2006 Air pressure should be measured only when the tires are cold, that is, when they have not been driven for at least three hours. If you want to fill your tires at the gas station, measure them at home (where they are cold) and note the difference from the recommended pressure. For example, if 35 psi is recommended, but yours measure 31 psi when cold, the difference is 4 psi. After you've driven to the gas station, measure again -- since the tires are now warm, they will be more than the 31 psi you noted at home. Simply add your difference (4 psi in this example) to the pressure you initially measure at the gas station and pump away.

Anonymous said

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on 8/8/2006 The cashier at gas pumps can activate the air compressor from inside the store. Fill up the tank and then ask them to turn it on. It's complimentary.

Anonymous said

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on 3/17/2006 If you are at a gas station with a coin operated air pump, before you insert the coin, make sure you have removed all the tire valve caps and brought the hose close to the tire that is farthest from the pump.

Anonymous said

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on 1/19/2006 Get a small portable air compressor, which may cost only $10 or so in thrifty dollar stores. It's a lot better than getting to the gas station to fill your tires.

Anonymous said

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on 1/9/2006 It's a common misconception when filling tires that they should be filled to the PSI stamped on the side of the tire. The PSI that should be used is usually found inside the door jam, sometimes on newer vehicles it is also on the inside of the fuel door.
My SUV even requires different pressures, front and rear.