How to Check and Add Air to Car Tires

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

Difficulty: Easy

Instructions

Things You'll Need:

• Tire Gauges
• Tread Depth Gauge

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

2. 
    

   Remove the cap from the valve on 1 tire.

3. 
    

   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.

4. 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.

5. 
    

   Replace the valve cap.

6. 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).

7. 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.

8. 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.

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[irauto1]

on 7/21/2009 Note that different recommended tyre pressures, for the front and rear tyres, are quite common and may/will also vary depending on the vehicle loading.

[irauto1]

on 7/21/2009 Check vehicle Tyre Pressures only when tyres are cold.
Ensure that tires are cold before checking the pressures. As the pressure in a tire increases as a tire gets hot/hotter, checking the pressure/s when hot, may indicate that the tire pressure/s are too high and exceed their recommended pressures - ie.over inflated. In which case, one may unwittingly need to let them down slightly so that they appear to be at their correct pressure/s - and when they are cold again they will actually be under inflated.

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.

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.

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.