Reading Your Tire
Aramid: A synthetic fiber that is, per weight, stronger than steel.
Used in tire construction and provides excellent high tensile
strength to weight.
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.
Block Design: A tire tread pattern made of raised rubber- compound segments.
Blocks: The individual, raised rubber-compound segments making up the tread of a tire.
Carcass: That portion of a tire that is the foundation for the tread, belts, bead and sidewall.
Casing: The structure of tire cords locked around wire beads.
Chafer: A finishing strip of calendered fabric used to protect the tire's bead area from the rim.
Compound: The general term referring to the chemical formula for the tread material.
Drive Wheel(s): The wheel(s) that provide the power or driving force for a vehicle.
Filler: The material used to fill the area above the bead between the outer and inner portion of the sidewall. Also used in enlarged form to stiffen the lower sidewall of a tire.
Grooves: Circumferential channels between the tread ribs of a tire.
H-Speed or H-Performance Rated: A speed category for tires with a maximum speed capability of 130 MPH.
High Performance Tire: 1. In the tire industry, those tires with speed ratings of S or greater and aspect ratios of 70 or less. 2. At Yokohama, those tires with an aspect ratio of 70 or less and a speed rating of H, V or Z.
Hydroplaning: Loss of traction at high speeds caused by a wedge of water that lifts a tire off the road surface.
Light Truck Tires: Tires designed for off-the-road and on/off-the-road use on sport/utility, small commercial and recreational vehicles.
Load Range: 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.
S-speed or S-performance rated: A speed category for tires with a maximum speed capability of 112 MPH.
Series: A numerical representation of a tire's aspect ratio; for example, 50 series.
Shoulder Blocks: Raised rubber-compound segments on the part of the tire tread nearest the sidewall.
Sipes: Slits in the tire tread. Small cuts in the surface of the tread to improve traction.
Steel Belt: A belt material used in radial tires. Its high stiffness provides good handling and low treadwear.
Steer Wheel(s): The wheel(s) that direct the course of a vehicle.
Stud Holes: Small cavities along a tire's tread designed to hold tire studs for increased traction on snow-covered surfaces.
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.
Trailer Wheel(s): The wheel(s) of a trailer unit that neither provide power nor direct the course of a vehicle.
Tread Blocks: Raised rubber-compound segments on the outside visible part of a tire.
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.
V-Speed or V-Performance Rated: A speed category for tires with a maximum speed capability of 149 MPH.
Varied-Pitch Ratio: Variations in angles and sizes of a tire's tread elements that reduce ride noise levels.
Z-Speed or Z-Performance Rated: A speed category for tires with a maximum speed capability of 149+ MPH.