Millions of tires are discarded every year, and an entire industry has developed to put them back in service by replacing the worn tread areas with new ones. The retreading process involves grinding the tread of an otherwise sound old tire and winding a strand of uncured rubber around the tire.
Then the tire is placed in a mold, where the rubber is cured under heat and pressure and the tread itself is shaped. Finally, the tire is painted. For many years, retreads had a reputation of being unreliable, and most consumers assumed that the strips of tread they saw littering the highways came from retreaded tires that had disintegrated on the road. But today, advances in retreading have raised their quality.
Although they are now hardly used on passenger vehicles, and high-performance vehicles are probably better off with new tires, most large commercial trucks (such as semis) use them, as do virtually all the world’s airlines. Retreaded tires are also used on school buses, racing cars, taxis, trucks, and federal and U.S. military vehicles.
Caring for Your Tires
Tires don’t require a great deal of maintenance, but the jobs in this section will pay off handsomely by increasing your tires’ longevity, handling, and performance as well as providing you with a more comfortable ride.
Checking tire inflation pressure
The single most important factor in caring for your tires is maintaining the correct inflation pressure. True, most newer vehicles have the built-in pressure-monitoring systems described earlier in this chapter, but there are still many vehicles on the road without them. If your vehicle doesn’t have a pressure monitoring system, you should
check your tires at least once a month and before every long trip to see that they’re properly inflated. Tires that are correctly inflated tend to wear properly in spite of minor weather ups and downs. Underinflated tires wear out faster, create excessive heat, increase fuel consumption, and make the vehicle harder to handle.
Overinflated tires can blow out more easily, wear out faster, and make the vehicle unstable and unsafe to handle. The section “Checking your tires for wear,” later in this chapter, helps you check for signs of these problems and tells you what to do about them.
Check the tire pressure in the morning before you start out or when you’ve driven less than a mile. If you drive more than that, your tires will heat up and the air will expand, so you won’t get an accurate reading. If the weather has changed radically, it’s time to check the pressure again.
In hot weather, the pressure in your tires rises by one pound per square inch (psi) of pressure for every 10°F as the air in them heats up and expands. This can result in overinflation. Conversely, in cold weather, the pressure falls by one degree for every 10° drop as the cold air contracts, so your tires can end up underinflated.
Therefore, if the weather gets very cold — and it looks as though it will stay that way for some time — and if you get a low reading, you may want to add a bit of air to your tires to bring the pressure back up.
You can find the tire decal on one of the doors, door pillars, glove box, console, or trunk. Sometimes the tire decal specifies one pressure for the front tires and a different pressure for the rear tires.
Don’t consult the tire’s sidewall for the proper inflation pressure. The sidewall lists the maximum pressure that the tire is capable of handling, not the pressure that’s best for performance and wear (unless you’re carrying heavy loads).