Other Common Terms
Aspect Ratio A numerical term which expresses the relationship between the section height of the tire and the cross section width. The lower the aspect ratio, the wider the tread and the shorter the sidewall.
Hydroplaning Associated with driving on rain-slicked roads with worn tires. It is the lifting action on a tire when water pressure forces the tire upward, leaving a cushion of water between the tire and road surface.
Load Index A numerical code associated with the maximum load a tire can carry at the speed indicated by its speed symbol.
Load Range A term which is gradually replacing the term "Ply Rating" and which is indicated as Standard Load (SL) and Extra Load (XL) for auto tires and Load Range C, D etc. for light truck tires. (The carrying capacity of the tire at specific air inflation pressures.)
PSI Pounds per square inch - used to measure air pressure in a tire.
Service Description A mark consisting of the load index and speed symbol, i.e. 87S.
Speed Rating A system to establish and label the high-speed capability of a tire based on laboratory testing.
*Kelly-Springfield does not recommend the use of any of its products in excess of legal speed limits.
Tread Depth A mound of rubber in the tread measured in 32nds of an inch from the tread surface to the bottom of the tread grooves.
Tread Design The pattern of grooves and tread elements.
Tread Wear Indicator Narrow bars of rubber molded into the tread at a height of 2/32nds of an inch. When this appears, it is time to replace the tire.
UTQG Stands for Uniform Tire Quality Grading, a quality rating system developed by the Department of Transportation (DOT). For more information on UTQG continue here.
Wheel Alignment The measuring, analyzing and setting of angles to predetermined specification to help ensure maximum tire service life, vehicle handling and safety. Proper wheel alignment is attained when each wheel's position, relative to the vehicle and specification, is correct.
Four-Wheel Alignment Four-wheel alignment is the setting of all four wheels to specifications and referenced to the vehicle centerline.
Two-Wheel Alignment Two-wheel alignment is normally performed on solid axle rear wheel drive vehicles, and is the setting of the front wheels relative to one another.
Wheel Balancing Adding external weights to compensate for unequal distribution of tire and wheel weight. Unbalanced tire and wheel assembly is balanced by clamping appropriate metal weight to the rim. |