A tires speed rating denotes the maximum permitted speed that the tire can sustain for 10 minutes without being in danger. Speed ratings are determined through lab tests that simulate road performance.
The Uniform Tire Quality Grading System (UTQGS) allows consumers to compare tire treadwear, traction performance, and temperature resistance. The U.S. Department of Transportation National Highway Safety Administration mandates tire manufacturers to grade their tires in these three areas and place the information on the sidewall of the tire.
Most tires are covered by a limited warranty that certifies the workmanship and the overall quality of the tire. Limited warranties typically last 4 to 6 years from the purchase date, or until the tires original tread is worn to 2/32nds of inch.
Ply rating identifies the load carrying capabilities of a tire in terms of plies. The ply rating originally referred to the number of cotton layers used to strengthen a tires casing.
Popular types of tires are All Season, Touring, Performance, Ultra High Performance, Original Equipment, Winter, All Terrain, Mud, and Commercial. Most sacrifice some aspect of their performance in order to strengthen another to match the expectations and driving styles of different people and vehicles.
A tires load index indicates the amount of a weight each tire can support. The higher a tires load index number, the greater the load-carrying capabilities.
