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Tires Last Longer With Proper Care
Tire care starts where the rubber meets the road
by Peter D. du Pre
According to the tire experts at the Goodyear Tire and Rubber Co., taking proper care of your tires can prolong tread life by as much as 50 percent at virtually no extra cost! Taking just a few minutes a week, they say, to maintain proper inflation levels and check for unusual wear patterns will maximize safety, add thousands of miles to the tread life and help increase fuel economy.
Underinflated tires run hotter than properly inflated ones, developing excessive heat that leads to tire failure. An underinflated tire also wears abnormally, with the tread on the outside edges of the tire wearing faster than the tread in the center of the tire. Driving on underinflated tires can cost you up to a mile a gallon in fuel economy because it takes more fuel to overcome the rolling resistance of a partially inflated tire. It is also dangerous. Driving on underinflated tires adversely affects handling and the tire can overheat and blowout.
Apart from not filling them properly to begin with, tires lose air naturally, through a process called permeation and changes in the outside temperature can affect the rate at which your tires lose air. On the average, a tire will lose one or two pounds of air per month in cool weather, and more during the warmer months.
Overinflation, or putting too much air in the tire, is another common mistake. Putting too much air in a tire is almost as bad as not enough, resulting in premature tread wear in the center of the tire and increased operating temperatures that can, again, lead to a blowout. Also, don't make the mistake of thinking that if an underinflated tire costs you in fuel economy, an overinflated one will help your gas mileage. While it is true that an overinflated tire rolls more easily and can improve fuel economy a little, the costs of excessive tread wear and danger of blowout more than offset the small increase in fuel economy.
So, how do you tell if you've got the right amount of air in your tires? Well, you can't tell by looking at them. On today's low profile radial tires, it is almost impossible to tell when a tire is over or underinflated. In fact, most of the time a properly inflated tire will appear to be underinflated.
The Tire Industry Safety Council says that the only way to guarantee proper inflation is to check the tire placard located on the driver's doorpost, the fuel filler door, or inside the glove box and note the correct tire pressure for your vehicle. Then use an accurate tire pressure gauge to check the air pressure.
Don't rely on the air pump at the local quick-fill gas station. These convenient machines are infamous for being grossly inaccurate. A quality tire gauge can be purchased at any tire dealer or auto parts store for under $10. Keep it in the glove box and make it a ritual to check your tires once a week. If you just can't bring yourself to bend over and check the tires yourself, have them checked at a tire store. In fact, many tire stores will check air pressure and give a tire safety inspection for free.
Whether you check the tires or have them checked, be sure to do the job when the tire is cold -- in the morning before you've driven the car more than a mile or so. Drive more than this and you'll need to wait an hour or so to let the rubber cool off. The reason for this is that the air in the tire expands as it heats up, increasing pressure and giving you an inaccurate reading. If you must drive more than a mile to get air, check the pressure of each tire and record the amounts. Upon arriving at the air pump, check the pressure again and inflate the warm tire to a level that is equal to this warm pressure, plus the cold pressure reading you took earlier. Sound complicated? It isn't really. Let's assume that the correct inflation for your car's tires is 35 pounds per square inch (psi) and that the cold pressure reading was 29 psi on one tire. At the filling station, the warm pressure reading on that same tire might be 32 psi, but it is now 38 psi on the other tires. You need to add 6 psi to the low tire to bring it up to spec.
Another thing to remember is that the correct tire pressure for a given tire is determined by the tire type (all-season, high-performance) and by the vehicle's size and weight. That is why your neighbor's car can have the same size tires as your vehicle but the tire pressure ratings for the two vehicles may be different.
Other conditions that affect tire pressure are driving conditions and load. If you are doing a lot of high speed driving or carrying a lot of extra weight in the car, increase tire pressure by about 4 pounds to compensate. Under no circumstances, however, should you ever exceed the maximum inflation limit imprinted on the tire sidewall. If you aren't sure what the proper pressure is for the conditions and load you operate under, consult the tire information sticker on the doorpost, fuel filler door, or glove box, look in your owner's manual or call the local tire dealer.
Improper inflation levels aren't the tire's only enemy. Uneven tire wear such as cupping and feathering can be caused by a misaligned suspension, out-of-balance tires, as well as bad shock absorbers or struts. Correcting these problems will smooth out your ride, make your car safer and help extend tire life.
Another factor in extending tread life is tire rotation. Experts at the Rubber Manufacturers Association and the Tire Industry Safety Council recommend that tires be rotated every 6,000 to 8,000 miles. The vehicle owner's manual will show the correct rotation pattern and interval of change that's right for your car. While regular rotation of the tires helps extend tread life and promotes even wear, it will not cure uneven wear caused by other factors. If the tire is showing uneven or aberrant tread wear, the only cure is replacement.
With proper care, it is not uncommon to get 60,000, 70,000, or even 80,000 miles from a set of tires before the wear bars show through. These built-in indicators appear as strips that run across the tread pattern when it has worn down to 1/16th of an inch (1/4 inch for snow tires), and indicate that the tire's useful life is over. Driving on tires that have exposed wear bars is unsafe and illegal. Replace them with new treads as soon as possible; a bald tire is 44 times more likely to have a failure than a tire with legal tread on it.
If you aren't sure whether the wear bars are beginning to show or not, you can check tread depth using a penny. The distance between the edge of the coin and the top of President Lincoln's head is just about 1/16th of an inch. Insert the penny into a channel between the treads so that the President's head is at the bottom of the groove. If you can still see the top of Mr. Lincoln's head when the penny is in the groove, it is time to replace the tire.
The five minutes a week it takes to check and care for your tires will be more than offset by increased tire life, improved economy, increased safety, and peace of mind. Additionally, making your tires last as long as possible is the environmentally sound thing to do. Worn out tires are difficult to recycle. Keeping your vehicle's tires in good condition will keep one set of tires out of the tire dump over the life of your car.