Tire Glossary

Tire & Wheel Information
Glossary of Terms

Air Pressure
The measure of force exerted by the air inside a tire, typically measured in pounds per square inch (PSI), or kilopascals (kPa).
When opposite sides of a tire’s tread pattern are not identical.
Also known as rearspacing, this is the distance from the mounting pad to the back edge of the rim. Not to be confused with wheel offset.
The even distribution of weight on a mounted wheel and tire.
The part of the tire in contact with the wheel flange. It is made of high tensile steel wires shaped to fit the rim and hold the tire on the wheel. The steel wires are wrapped in woven fabric and held in place by the plies.
Bias Tire
A tire constructed with plies laid out in alternating directions in angles about 30-40 degrees to the center line of the tire. The plies form a criss-cross pattern that is typically suited more towards off road driving.
Bolt Circle
The number of lug holes on the diameter of the imaginary circle that each lug hole is centered upon.
Bolt Pattern
The arrangement of bolt holes on a wheel. Some wheels have more than one bolt pattern on the same wheel to accommodate multiple fitments.
Hub Centric
A situation wherein the center bore of the wheel is made to match up with the diameter of the automobile hubs; the wheel is then balanced by the center hold rather than the lug holes.
Hub Centric Rings (Hubrings)
Hard plastic or aluminum rings mounted on a vehicle’s hub before the wheel. This ensures that the wheel is perfectly centered on the vehicle’s hub, and also lessens the possibility of vibration when the tire and wheel are perfectly balanced.
The distance from the mounting surface of the wheel to the true centerline of the rim. A positive offset means the wheel’s mounting surface is positioned in front of the true centerline of the rim and tire assembly, bringing the tire into the fender well more. Conversely, a negative offset means the wheel is behind the true centerline of the rim and tire assembly, causing the tire to stick out away from the vehicle.
Plus Sizing
Changing the original stock tire size of your vehicle in order to enhance vehicle performance by allowing for fitment of larger wheels and tires. It is recommended that you keep the overall tire diameter within 3% of OEM tire size to prevent problems with transmission, gas mileage, and braking.
The most common measurement unit for tire pressure that stands for pounds per square inch. PSI is intended to measure the force exerted by the air inside a tire.
Radial Tire
Tires built with perpendicular plies across the crown of the tire, effectively strengthening the tread for street driving. These tires also require belt plies going circumferentially around the tire for solidarity purposes.
Rim Diameter
The distance between bead seat to bead seat at bead seat radius.
Rim Width
The measurement between the flanges of a rim.
The side portion of a tire between the tread and bead.
Small slits in a tire’s tread that help push water away from the crown of the tire for improved wet traction. They also provide biting edges for ice and snow traction.
Tread Blocks
Raised rubber compound segments in a tire’s tread. Blocks of varying sizes, shapes, and designs are typically used for a variety of effects, such as better wet traction, or stronger rock-crawling ability.RETURN TO FAQ RESOURCE PAGE

Tread Depth
The distance from the top of the tread to the grooves in a tire. The measurement is taken at the centerline of a tire and is measured in thirty-secondths of an inch.
Tread Pattern
The arrangement of grooves, blocks, sipes, and channels on the tread of a tire that provide a varying degrees of effects on traction, tread life, and other tire factors.
Wheel Offset
The distance between the wheel mounting surface where bolted to the hub of the drum and centerline of the rim. This determines a vehicle’s “track,” or distance between tires on each axle. Keep the wheel offsets as close to original as possible to avoid steering and wheel bearing difficulties.
Wheel Width
The distance between the inside of the rim flanges rounded to the nearest half inch that helps to ensure that the wheel width is the appropriate size for your tire. Each tire has a minimum and maximum wheel width limit.
Zero Offset
A condition where the wheel’s mounting surface coincides with the centerline of the wheel.