Tire Terminology and Definitions
Air Pressure:The amount of air inside thetire pressing outward on each square inch of thetire. Air pressure is expressed in pounds persquare inch (psi) or kilopascal (kPa).
Accessory Weight:This means the combinedweight of optional accessories. Some examples ofoptional accessories are, automatic transmission,power steering, power brakes, power windows,power seats, and air conditioning.
Aspect Ratio:The relationship of a tire’s heightto its width.
Belt:A rubber coated layer of cords that is locatedbetween the plies and the tread. Cords may bemade from steel or other reinforcing materials.
Bead:The tire bead contains steel wires wrappedby steel cords that hold the tire onto the rim.
Bias Ply Tire:A pneumatic tire in which the pliesare laid at alternate angles less than 90 degreesto the centerline of the tread.
Cold Tire Pressure:The amount of air pressure ina tire, measured in pounds per square inch (psi) orkilopascals (kPa) before a tire has built up heatfrom driving. SeeInflation - Tire Pressure onpage 6-54.
Curb Weight:The weight of a motor vehicle withstandard and optional equipment including themaximum capacity of fuel, oil, and coolant,but without passengers and cargo.
DOT Markings:A code molded into the sidewallof a tire signifying that the tire is in compliancewith the U.S. Department of Transportation (DOT)motor vehicle safety standards. The DOT codeincludes the Tire Identification Number (TIN),an alphanumeric designator which can also identifythe tire manufacturer, production plant, brand,and date of production.
GVWR:Gross Vehicle Weight Rating. SeeLoading the Vehicle on page 5-18.
GAWR FRT:Gross Axle Weight Rating for thefront axle. SeeLoading the Vehicle on page 5-18.
GAWR RR:Gross Axle Weight Rating for therear axle. SeeLoading the Vehicle on page 5-18.
Intended Outboard Sidewall:The side of anasymmetrical tire, that must always face outwardwhen mounted on a vehicle.
Kilopascal (kPa):The metric unit for air pressure.
Light Truck (LT-Metric) Tire:A tire used onlight duty trucks and some multipurpose passengervehicles.
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