Tire wear can be equalized by switching the position of the tires about every 6000 miles, (9700 km). Including a conventional spare in the rotation pattern can give up to 20% more tire life.
Due to their design, radial tires tend to wear faster in the shoulder area, particularly in the front positions. Radial tires in non-drive locations, may develop an irregular wear pattern that can generate tire noise. It was originally thought the radial tires should not be cross-switched (from one side of the vehicle to the other); because of their wear patterns and because they would last longer if their direction of rotation is not changed. The manufacturer's tire rotation recommendations for most late model vehicles covered by this guide now allows for, and even suggests, cross-switching radial tires to allow for more uniform tire wear.
If you have any doubt as to the correct rotation pattern for the tires which are currently mounted on your vehicle, consult the tire manufacturer or one of their facilities for recommendations
When buying new tires, give some thought to the following points about tire design, especially if you are considering a switch to larger tires or a different profile series:
- All four tires must be of the same construction type. This rule cannot be violated. Radial, bias, and bias belted tires must not be mixed.
- The wheels should be the correct width for the tire. Tire dealers have charts of tire and rim compatibility. A mismatch will cause sloppy handling and rapid tire wear. The tread width should match the rim width (inside bead to inside bead) within an inch. For radial tires, the rim width should be 80% or less of the tire (not tread) width.
- The height (mounted diameter) of the new tires can change speedometer accuracy, engine speed at a given road speed, fuel mileage, acceleration, and ground clearance. Tire manufacturers furnish full measurement specifications.
- The spare tire should be usable, at least for short distance and low speed operation, with the new tires.
- There should not be any body interference when loaded, on bumps or in turns.
Store the tires at the proper inflation pressure if they are mounted on wheels. Keep them in a cool dry place, laid on their sides. If the tires are stored in the garage or basement, do not let them stand on a concrete floor. Set them on strips of wood.
Tire inflation is the most ignored item of auto maintenance. Gasoline mileage can drop as much as 0.8% for every 1 pound per square inch (psi) of under inflation.
Two items should be a permanent fixture in every glove compartment: a tire pressure gauge and a tread depth gauge. Check the tire air pressure (including the spare) regularly with a pocket type gauge. Kicking the tires won't tell you a thing, and the gauge on the service station air hose is notoriously inaccurate.
The tire pressures recommended for your vehicle are usually found in the owner's manual. Ideally, inflation pressure should be checked when the tires are cool. When the air becomes heated it expands and the pressure increases. Every 10° rise (or drop) in temperature means a difference of 1 psi, which also explains why the tire appears to lose air on a very cold night. When it is impossible to check the tires cold, allow for pressure build-up due to heat. If the hot pressure exceeds the cold pressure by more than 15 psi, reduce your speed, load or both. Otherwise internal heat is created in the tire. When the heat approaches the temperature at which the tire was cured, during manufacture, the tread can separate from the body.
Before starting a long trip with lots of luggage, you can add about 2-4 psi to the tires to make them run cooler, but never exceed the maximum inflation pressure on the side of the tire.
All tires made since 1968, have 7 built-in tread wear indicator bars that show up as 1 / 2 in. (6mm) smooth bands across the tire when 1 / 16 in. (1.5mm) of tread remains. The appearance of tread wear indicators means that the tires should be replaced. In fact, many states have laws prohibiting the use of tires with less than 1 / 16 in. (1.5mm) tread.
You can check your own tread depth with an inexpensive gauge or by using a Lincoln head penny. Slip the Lincoln penny into several tread grooves. If you can see the top of Lincoln's head in 2 adjacent grooves, the tires have less than 1 / 16 in. tread left and should be replaced. You can measure snow tires in the same manner by using the tails side of the Lincoln penny. If you can see the top of the Lincoln memorial, it's time to replace the snow tires.
CARE OF SPECIAL WHEELS
If you have invested money in mag, aluminum alloy or sport wheels, special precautions should be taken to make sure your investment is not wasted, and that your special wheels look good for the lifetime of the vehicle.
Special wheels are easily scratched and/or damaged. Occasionally check the rim for cracks, damage or air leaks. If any of these conditions are found, replace the wheel. In order to prevent this type of damage, and the costly replacement of a special wheel, observe the following precautions:
Take special care not to damage the wheels during removal, installation, balancing etc. After removal of the wheels from the vehicle, place them on a rubber mat or other protective surface.
While the vehicle is being driven, be careful not to drive over sharp obstacles or allow the wheels to contact the shoulder of the road.
When washing, use a mild detergent and water. Avoid using cleansers with abrasives, or hard brushes. And a little polish after washing will help your wheels keep that new look.
If possible, remove your special wheels from the vehicle during the winter months, and replace them with regular steel rims. Salt and sand that is applied to the roadways for snow removal during these months can do severe damage to special wheels. Make sure that the recommended lug nut torque is never exceeded, or you may crack your wheels. Never use snow chains with special wheels.
If you intend to store the wheels, lay them flat on a protective surface and cover them. Do not stack them on top of each other and do not place anything else, except a protective cover, on them.