Tire Care Basics
the top of his head, it is time to replace the tires.
ROTATION
Rotating the tires at regular intervals achieves uniform wear for all tires. Approximately every 6,000 to 7,500 miles, the tires should be rotated. Depending on your car's maintenance schedule, you might find it helpful to rotate the tires at every other oil change.
For the exact pattern of rotation for your car, check your owner's manual or with a tire professional.
GENERAL CARE
Only clean your tires with soap and water. Many commercial cleaning products and shine enhancers contain a petroleum base product which may contaminate or otherwise compromise the rubber, resulting in cracking or other damage.
READING A TIRE SIDEWALL
It may look confusing, but the letters and numbers on the sidewall of your tires really do mean something. As an example:
P215/65R15 89H
P = Passenger. On trucks, this might instead read LT for Light Truck.
215 = Tire width in millimeters. To convert this to inches, divide by 25.4
65 = Aspect ratio. This is the ratio of the sidewall height to width.
R = Radial. You might also see B for belted bias, or D for diagonal bias construction.
15 = Wheel diameter in inches.
89H = Service description. 89 is the load index, or how much weight the tire will support. H is the speed symbol, or the maximum speed a tire (not the car!) is capable of sustaining. These translate as follows:
Q = 99mph; R = 106 mph; S = 112 mph; T = 118 mph; U = 124 mph; H = 130 mph; V = 149 mph; Z = 149+ mph
If you haven't had enough alphabet soup yet, you might also see the Uniform Tire Quality Grading System markers.
Treadwear: This number is a basis of comparison, not an absolute. It is set by each manufacturer and applies to that manufacturer's line of tires only. The baseline is 100. For example, if the number is 160, you can estimate 60% more treadlife than the baseline.
Traction: This is a measurement of the tire's ability to stop on wet pavement. The scale runs from AA (best) through C (worst).
Temperature: The ability to resist the effects of heat. C is the minimum required by US federal regulations. B is better and A is the best.
For more information, check out http://www.tirerack.com for great tire care tips, info and even info on buying tires by mail. Also comparison shop at http://www.etires.com Also check out the Tire Industry Safety Council at http://www.tisc.org
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