Plus-Sizing: An option allowing drivers to customize their vehicle by mounting low-profile tires on wider rims of greater diameter, usually enhancing vehicle appearance, handling and performance.
Radial Tire: A tire built with casing plies that cross the crown at an angle of 90 degrees.
Rotation: The changing of tires from front to rear or from side-to-side on a vehicle according to a set pattern; provides even treadwear.
Shimmy: Wobbling of wheels from side-to-side on a vehicle. Shimmying can be caused by a variety of factors, including improperly balanced tires, poor alignment and bent wheels.
Shoulder: The area of a tire where the tread and sidewall meet.
Sidewall: That portion of a tire between the tread and the bead.
Sipes: Special slits within a tread block that increase wet and snow traction. Sipes provide more biting edges and allow for the dispersion of water from under the tread surface.
Speed Rating: An alphabetical code (A-Z) assigned to a tire indicating the range of speeds at which the tire can carry a load under specified service conditions.
Tread: The area of a tire where the tread and sidewall meet.
Tread Rib: The tread section, usually composed of many tread blocks that run around the circumference of the tire, separated by the circumferential tread grooves.
Treadwear Indicator (Wear Bars): Narrow bands, sometimes called "wear bars," that appear across the tread surface of the tire when only 2/32 inch of tread remains.
Tread Width: The width of a tire's tread.
Traction: The friction between the tires and the road surface; the amount of grip provided.
UTQG: Uniform Tire Quality Grade. A government-mandated tire rating system based on a tire's performance in treadwear durability, traction, and temperature resistance. UTQG ratings are branded on a tire's sidewall.