As reported today on "Good Morning America," checking your tires is important for the safety of you and your family. But 64 percent of drivers do not know how to check their tires' tread depth, according to a tire trade association, and 85 percent do not know how to check their tire pressure.
Indeed, 11 percent of vehicles have at least one bald tire and 49 percent have at least one underinflated tire, according to the Rubber Manufacturer's Association. When "Good Morning America" tested 100 cars in a Virginia parking lot, our own results were much the same. Eleven percent of the cars failed our tread depth test and 45 percent failed our tire pressure test.
Under-inflation and tire tread may not seem like a big deal but as Dave Craig of Cooper Tire explained, your tires are "really the only piece of the vehicle that touches the road , and keeps them on the road. … Maintenance level and time put into that is very important."
Here are some tips to help get you started on checking your tires.
Tire Inflation Tips:
Tire pressure is measured in PSI or pounds per square inch.
Ideally your tires should be at the precise pressure in your owner's manual. Find the ideal pressure in your owner's manual, glove box or on the door jam of the car. Contrary to popular belief, the pressure listed on the tire itself is not the optimum pressure. It's the maximum allowed pressure.
Overinflation causes the center of the tire to bulge out and rub the road unevenly, wearing your tires our prematurely.
Underinflated tires can cause handling problems, or even a blowout.
Always check the pressure when the tires are cold for an accurate reading.
The Rubber Manufacturers Association recommends you check your tire pressure once a month.
It's especially important to check your tire pressure when the seasons change because outdoor air temperature affects tire pressure. Typically, for every 10 degree change in outdoor temperature, your tires' pressure will go up (in summer) or down (in winter) by one PSI.
Some service centers charge extra to inflate your tires with nitrogen instead of regular air, claiming they will hold their inflation level better. While it won't void your warranty, studies have shown nitrogen does not make a dramatic difference, so there's no need to spend the extra money.
"Your tire is designed to function … at the specified air pressure," former race car driver and Cooper Tire adviser Johnny Unser said. So if your tires are underinflated, "you're going to sacrifice a little bit on safety, you're going to sacrifice a little bit on mileage and you're going to sacrifice a little bit on performance."
Bald tires are the biggest safety threat of all. Tread is crucial for absorbing water as you drive through it, providing the best handling during wet conditions. On a slick test track, a car with a healthy amount of tread will perform fine, but one with bald tires typically spins out.