Tire Dictionary

Air Pressure - You need to know what the proper inflation air pressure is for your particular vehicle. You can find this information in one of the following places: vehicle’s owners manual, on the inside of the driver side vehicle door, inside the fuel hatch filter flap (on some vehicles) or inside the glove compartment (on some vehicles). Do not look on the tire! There will be a number there but that pertains to the maximum tire inflation pressure not the inflation pressure for your particular vehicle/driving conditions. Once you have determined the proper inflation air pressure for your vehicle you are ready to check your tire pressure.

Alignment of Vehicle – Complex suspension angles that are being measured and a variety of suspension components that are being adjusted. This makes an alignment an important suspension-tuning tool that greatly influences the operation of the vehicle's tires.

All Season Tires – tires designed to perform in all season conditions including: wet, dry, ice, snow, etc.

ABS/Anti-Lock Brake System - allows the driver to maintain steering control under heavy braking by preventing a skid and allowing the wheel to continue interacting with the road surface as directed by driver steering inputs.

ASR/Anti-Slip Control - A method for preventing the drive wheels of a vehicle from spinning

Aquaplaning - of a vehicle's tires occurs when a layer of water builds between the rubber tires of the vehicle and the road surface, leading to the loss of traction and thus preventing the vehicle from responding.

Bead – part of the tire that meets the wheel (the tire's inside edge).

Braking Distance – distance a vehicle will travel from the time its brakes are fully applied until it actually stops.

Casing – the outermost covering of a tire.

DOT Serial Number – useful for identifying tires in a product recall and located on the tire sidewall.

ESP/Electronic Stability Program - a computerized technology that improves the safety of a vehicle's stability by detecting and minimizing skids.

Emergency Mobility Systems – With this system when all air pressure is lost the rim does not destroy the tire. The journey can be continued without changing the tire - over a limited distance at a restricted speed.

Load Index, Ply Rating or Load Range – carrying capacity of tire, found on sidewall.

Mixing Tires – all four tires should be the same speed rating, size, and construction, but if not the lower speed tires should be in the front.

Radial Tires - Radial tires have body cords that run across the tire nearly perpendicular to the beads.

Reinforced or XL (extra load) Tires – tires designed to carry and support more weight than tires of the same size.

Revolutions Per Mile (RPM) - The number of revolutions a tire makes in one mile, at a given load, speed and inflation.
Rolling Resistance – resistance occurring when a tire rolls on a flat surface.

Speed Symbol – can be found on the tire sidewall that shows the maximum speed that can be maintained.

Temporary Spare Tires – tires that are designed to carry the same load as your normal tire but do not have the same life span as a normal tire and must be replaced as soon as possible.

Toe – the difference between the centerline of the tires and the axle.

Tread – rubber on the circumference of the tire that makes contact with the road.

TWI (Tread Wear Indicator) - bars made of hard rubber lying crossways across the tread. You can't see them on new tires, but as the tread wears down, they become visible.

Tire Size Designation - located on the sidewall, provides a significant amount of information about the tire's intended purpose, dimensions, load capacity and high temperature/high speed durability.

Tire Storage – tires need dry, cool storage space. Also do not stack to many tires on top of one another as this can cause wear to the bottom one.

UTQG (Uniform Tire Quality Grading)- rating based on the tire treadwear , traction, and temperature under controlled conditions.

Valve – allows the tire to be filled with air.

Valve Cap – protects the valve from outside influences such as dirt, dust, water, etc.

Winter Tires – tires designed to specifically perform in snow and icy conditions.