Checking tire air pressure with a pressure gauge

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Air Pressure and Tire Longevity

When's the last time you checked the air pressure in your tires? If you're like most people, it's been a while. And like most people, your tires are probably under-inflated, too.

Once a month, check the air pressure with a tire pressure gauge when the tires are cold. It's best to do it in the morning before the car's been driven anywhere at all or at least a few hours after its last trip. Even a couple miles on the road can warm up the air inside the tire, causing it to expand and giving you an inaccurate reading. Warm summer days will expand the air inside the tires, too. A cold reading will give an accurate measure of pressure and, once filled, leave room for expansion while you're driving.

If once a month seems excessive, keep in mind that tires can lose one or two pounds of pressure a month. Neglecting this chore for six months means there's probably a little flat spot on the bottom of the tire where it meets the road. Having more tire in contact with the road means more surface area to wear out -- not to mention the fact that it can negatively affect your gas mileage, too.

Newer cars equipped with tire pressure monitoring systems (TPMS) lend a hand in the air pressure department. The basic systems alert the driver when a tire is low and going flat with an exclamation point inside a tire symbol on the dashboard. Other more sophisticated systems offer the tire pressure readings for each tire -- no pressure gauge required.

Once your tires are properly inflated, they should be properly aligned. On the next page, let's see how that can affect tire longevity.