There are many compentents to a tire. Below is a glossary of terms and definitions for
commonly and not so commonly heard terms when it comes to tires.
- ALIGNMENT: When all wheels on the vehicle are adjusted so that they are pointed in the optimum direction relative to the road and each other.
- ALL-SEASON TIRES: Tires that provide a good balance of traction in rain or snow with good tread life and a comfortable, quiet ride.
ASPECT RATIO: An expression representing the height of the sidewall of a tire in terms of a percentage of tire's width.
ASYMMETRIC: When opposite sides of a tire's tread pattern are not identical.
- BELT: A rubber-coated layer of cords that is located between the body plies and the tread. Cords are most commonly made from steel but may also be made from fiberglass, rayon, nylon, polyester or other fabrics.
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- BIAS- PLY: A type of tire with crossed layers of ply cord running diagonally to the center line of the tread.
- COLD INFLATION PRESSURE: The amount of air pressure in a tire, measured in pounds per square inch (psi) before a tire has built up heat from driving.
COMPOUND: The general term referring to the chemical formula for the tread material.
GROOVES: Channels between the tread ribs of a tire.
HIGH PERFORMANCE TIRE: In the tire industry, those tires with speed ratings of S or greater and aspect ratios of 70 or less. 2.
HYDROPLANING: Loss of traction at high speeds caused by a wedge of water that lifts a tire off the road surface.
TRUCK TIRES: Tires designed for off-the-road and on/ off-the-road use on sport/utility, small commercial, and recreational vehicles.
LOAD RATING: A method of rating a tire's load-carrying capacity (denoted by letters such as B, C, D, etc.) with respect to its ply rating.
LOW-PROFILE: A term describing a tire with a low relative aspect ratio or series classification.
METRIC TIRE SIZE SYSTEM: A tire sizing system using the section width (mm), aspect ratio, speed category, tire construction, and the rim diameter (inches). Example: 185/70SR13.
P-METRIC SYSTEM: A tire sizing system using the section width (mm), aspect ratio, type of tire construction, and rim diameter (inches). Example: P225/70R15.
PASSENGER CAR TIRE: Automobile tires featuring aspect ratios of 70 or greater, using a taller profile for increased ride comfort.
PLY: A layer of rubber-coated fabric or wire making up the tire casing.
RADIAL TIRE: A tire built with casing plies that cross the crown at an angle of 90 degrees.
RIBS: Parts of a tire tread pattern created by grooves that run circumferentially around the tire.
SERIES: A numerical representation of a tire's aspect ratio; for example, 50 series.
STEEL BELT: A belt material used in radial tires. Its high stiffness provides good handling and low treadwear.
TIRE PROFILE: A term representing the portion of a tire measured as its aspect ratio or series.
TOURING PERFORMANCE TIRE: A tire providing the ride comfort of a passenger car tire, yet possessing high performance tire characteristics.
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.
Z-SPEED OR Z-PERFORMANCE RATED: A speed category for tires with a maximum speed capability of 149+ MPH.
