How to check your tires for pressure, tread and damage

A tire gauge and a penny are all you need to check a car's tires. Do it once a month. Tires at the right pressure also save gas, improving mileage by 0.6 percent on average and up to 3 percent in some cases.

What you need

• A tire pressure gauge
• A penny
• An air pump, at home or at a gas station
• The owner's manual, for the tire size and the rotation interval

Steps

1. 1

   Find the right pressure

   The right pressure is on a sticker in the driver's door jamb or the glove box. The number on the tire's sidewall is the most the tire can hold, not the pressure to fill it to.

   2 min

2. 2

   Check the pressure while the tires are cold

   Check before you drive, or after the car has sat for at least three hours. Press the gauge onto each valve stem and read the number.

   5 min

3. 3

   Fill any tire that's low

   Add air to the door-jamb number, then check again. Each 1 psi drop in average pressure lowers gas mileage by about 0.2 percent.

   5 min

4. 4

   Check the spare

   A tire loses air even when it isn't used, so check the spare's pressure and condition every month too.

   2 min

5. 5

   Check the tread with a penny

   Put a penny into a tread groove with Lincoln's head pointing down. If you can see the top of his head, the tread is below 2/32 of an inch and the tire is worn out. Tires also have treadwear bars, small raised strips across the grooves. When the tread is level with them, the tire is worn out.

   3 min

6. 6

   Look for damage

   Look along each sidewall and across the tread for bulges, cuts and cracks.

   3 min

7. 7

   Check the readings

   Each tire, spare included, reads the door-jamb number cold, and every tread covers the top of Lincoln's head.

   1 min

Rotation and alignment

Have the tires rotated on the interval in your owner's manual, or every 5,000 to 8,000 miles if the manual doesn't give one. If the car pulls to one side, have the alignment checked.

Load and temperature

Check the pressure before you carry a heavy load or tow a trailer. Passengers count toward the load, and the owner's manual gives the limit. Tire pressure also moves with the weather, rising in warm weather and falling in cold, by one to two psi for every 10 degrees.