See Figures 1, 2, 3 and 4
Inspect your tires often for signs of improper inflation and uneven wear, which may indicate a need for balancing, rotation, or wheel alignment. Check the tires frequently for cuts, stone bruises, abrasions, blisters and for objects that may have become embedded in the tread. More frequent inspections are recommended when rapid or extreme temperature changes occur or where road surfaces are rough or occasionally littered with debris. Check the condition of the wheels and replace any that are bent, cracked, severely dented or have excessive run-out.
The tires on your car have built-in wear indicators molded into the bottom of the tread grooves. The indicators will begin to appear as the tire approaches replacement tread depth. Once the indicators are visible across 2 or more adjacent grooves and at 3 or more locations, the tires should be replaced.
Wear that occurs only on certain portions of the tire may indicate a particular problem, which when corrected or avoided, may significantly extend tire life. Wear that occurs only in the center of the tire indicates either overinflation or heavy acceleration on a drive wheel. Wear occurring at the outer edges of the tire and not at the center may indicate underinflation, excessively hard cornering or a lack of rotation. If wear occurs at only the outer edge of the tire, there may be a problem with the wheel alignment or the tire, when constructed, contained a non-uniformity defect.
See Figure 5
Tire rotation is recommended every 6,000 miles or so, to obtain maximum tire wear. The pattern you use depends on whether or not your car has a full-sized usable spare or a undersized "donut'' spare. Because the compact or donut spare tire is designed for limited emergency use, it should not be included in normal tire rotation.
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 car to the other); because of their wear patterns and that they would last longer if their direction of rotation is not changed. The manufacturer's recommendations for tire rotation allows and even suggest cross-switching radial tires to allow for more uniform tire wear.
Some specialty aftermarket tires may be directional, meaning they may only be mounted to rotate in one direction. Some snow tires and special performance tires/wheels will fall into this category and will be marked with directional rotation arrows on the tire sidewalls. NEVER switch the direction of rotation on tires so marked or poor performance/tire damage could occur. This should be taken into consideration in choosing a rotation pattern for directional tires.
See Figure 6
When buying new tires, give some thought to the following points, 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 or vehicle handling and safety may be seriously jeopardized.
- The wheels should be the correct width for the tire. Tire dealers have charts of tire and rim compatibility. A miss-match 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 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 shouldn't be any vehicle body interference when loaded, on bumps, or in turns. If the tire hits the wheel-well under load, wear and the possibility of a blow-out will be significantly increased.
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.
Tires should be checked weekly for proper air pressure. A chart, located either in the glove compartment and/or on one of the vehicle's doors or door jambs, gives the recommended inflation pressures. Maximum fuel economy and tire life will result if the pressure is maintained at the highest figure given on the chart. Pressures should be checked with the tires cold before driving 1 mile or more since pressure can increase as much as six pounds per square inch (psi) due to heat buildup as the tire is warmed. It is a good idea to have your own accurate pressure gauge, because many gauges on service station air pumps cannot be trusted. When checking pressures, do not neglect the spare tire. Note that some spare tires require pressures considerably higher than those used in the other tires.
While you are about the task of checking air pressure, inspect the tire treads for cuts, bruises and other damage. Check the air valves to be sure that they are tight. Replace any missing valve caps. Dirt and moisture gathering in the valve stem could lead to an early demise of the stem and a subsequent flat tire.
Check the tires for uneven wear that might indicate the need for front end alignment or tire rotation. Tires should be replaced when tread wear indicators appears as solid bands across the tread.
CARE OF ALUMINUM WHEELS
If your car is equipped with aluminum wheels from an aftermarket application, they are normally coated to preserve their appearance. To clean the aluminum wheels, use a mild soap and water solution and rinse thoroughly with clean water. If you want to use one of the commercially available wheel cleaners, make sure the label indicates that the cleaner is safe for coated wheels. Never use steel wool or any cleaner that contains an abrasive, or use strong detergents that contain high alkaline or caustic agents, as they will damage your wheels.