Glossary “tire placard” Definition:
A label that is permanently attached to the rear face of the driver’s door of most vehicles providing information such as maximum vehicle load, tire size, including spare, and cold inflation pressure, including spare.

Glossary “tire mixing” Definition:
Having more than one size tire on a vehicle. Tires should be replaced only with those recommended by the vehicle manufacturer. Using incorrect or improper tires can cause the vehicle to handle improperly and may result in an accident.

Glossary “tire motion forces” Definition:
Forces that affect a tire in motion, including centrifugal, acceleration, and deceleration forces.

Glossary “tire out of roundness” Definition:
Lateral or radial runout of a tire.

Glossary “tire performance criteria” Definition:
Information molded on the tire sidewall indicating that the tire meets the manufacturer’s performance standards for traction, endurance, dimensions, noise, handling, and rolling resistance.

Glossary “tire inflation label” Definition:
A label required by federal law and is usually placed on the inner glovebox door or on the a door post.

Glossary “tire life expectancy” Definition:
Expected service life of a tire, based on its tread wear rating and uniform tire quality grading.

Glossary “tire load range” Definition:
Load carrying capacity of a tire, expressed in letters A through L. The load range letters replace the older method of rating tire strength by the number of plies used in its construction.

Glossary “tire manufacturer’s code” Definition:
A term for manufacturer’s code.

Glossary “tire inflation” Definition:
Air pressure inside the tire, measured in pounds per square inch (psi) or kiloPascal (kPa), checked when tire is cool or has been driven less than one mile.

Glossary “tire deflection” Definition:
Difference between the free diameter (unloaded) and the rolling diameter (loaded) of the tire.

Glossary “tire design” Definition:
Three basic tire construction designs are based on the arrangement of the body plies: bias, belted radial, and belted bias. A bias-ply tire is constructed with the plies arranged on a bias crossing each other. A belted radial-ply tire is constructed with plies that run at right angles to the circumference of the tire. A belted bias-ply tire is constructed with reinforcing belts beneath the tread section.

Glossary “tire free diameter” Definition:
The free diameter of a tire is the distance of a horizontal line through the center of the spindle and wheel to the outer edges of the thread.

Glossary “tire function” Definition:
1). To cushion the vehicle ride to provide a comfortable ride for the occupant; reduces jolts to the vehicle caused by road irregularities. 2). To support the vehicle weight. 3). To develop traction to drive and steer the vehicle under a wide variety of road conditions. 4). To contribute to the directional stability of the vehicle, and absorb all the stresses of accelerating, braking, and centrifugal force in turns.

Glossary “tire coding” Definition:
Information required by federal legislation to be placed on all tires, such as: manufacturer and tire name, size designation, maximum load-carrying characteristics, limit, and range, a ten-digit DOT serial number indicating where and when it was made, and the letter A, B, or C, indicating conformity to a uniform tire quality grading system.

Glossary “tire concentricity” Definition:
Condition where the plies and/or belts are not level across the tire tread and are somewhat cone shaped. This causes a pull to one side as the car is driven straight ahead if the tires are on the front of the vehicle.

Glossary “tire construction” Definition:
Tire construction design has two wire beads, bead filler, liner, steel reinforcement in the sidewall, sidewall with hard side compound, rayon carcass plies, steel belts, jointless belt cover, hard under-tread compound, and hard high-grip tread compound.

Glossary “tire contact area” Definition:
The footprint, patch, or patch area of the tire that is in contact with the road surface when the tire is supporting the vehicle weight.

Glossary “tire chain” Definition:
Specialty chains which may be placed over the tires to improve traction when driving on ice or snow; typically used in emergency situations such as driving on snow-covered or ice-covered mountain roads.

Glossary “tire changer” Definition:
Machine for quickly dismounting and mounting tires on and off of wheels.