Air Pressure: The amount of air within a tire, measured in pounds per square inch (PSI).

All-Season Tire: A tire designed for use in various weather conditions.

Aspect Ratio: The ratio of a tire’s sidewall height to its width. It is measured in percentage (%).

Alignment: Adjusting the angles of the wheels to ensure proper tire contact with the road.

Alignment Shim: A set of tools used to adjust wheel alignment.

All-Terrain Tire: A tire designed for off-road and on-road use.

All-Weather Tire: A type of all-season tire with better wet and snow traction than the standard all-season tire.

Aquaplaning: A loss of traction on wet roads due to a film of water between the tire and the road surface.

Anti-Lock Braking System (ABS): The Anti-Lock Braking System (ABS) is a safety feature in vehicles that prevents wheels from locking up during braking, thereby maintaining traction and steering control.

Average Tread Depth (ATD): The measurement of the average depth of a tire’s tread.


Balancing: The uniform distribution of weight in a wheel and tire assembly.

Bead: The part of the tire that sits on the rim of the wheel.

Bead Seating: The process of properly fitting the tire bead to the rim.

Bead Wire: A steel wire located within the tire’s bead to help secure it on the rim.

Bead filler: A rubber compound placed inside the bead of a tire to provide stiffness and shape. It enhances the tire’s fit and performance on the wheel.

Bias-Ply Tire: A tire with cord plies that crisscross at an angle to the centerline.

Belted Tire: A tire with steel belts beneath the tread for added strength.

Block Tread: A tire tread pattern consisting of large, square tread blocks.


Caster: The angle of the steering axis when viewed from the side.

Camber: Camber is the angle of the wheels relative to the vertical axis of the vehicle when viewed from the front.

Carcass: The tire carcass is the internal framework of a tire, consisting of layers of fabric and cords.

Center Bore: The hole in the center of the wheel for hub mounting.

Chamfer: A beveled edge on a tire tread block for improved performance.

Circumferential Grooves: Long, continuous grooves running around the tire to channel water away.

Cold Inflation Pressure: The tire’s air pressure when it’s cold.

Contact Patch: The portion of the tire that makes contact with the road.

Cord Plies: Layers of fabric or steel within the tire that provide strength.

Cornering: Cornering refers to a vehicle’s ability to navigate turns and curves with stability and control.

Curb Rash: Damage to the wheel or tire caused by contact with a curb.


DOT Number: The Department of Transportation code on a tire for identification.

Dry Rot: Cracking and deterioration of the tire’s rubber due to age and exposure.

Dry Traction: Dry traction refers to a tire’s ability to grip and maintain stability on dry roads.


Flat Spot: A portion of the tire tread that has become flat due to extended parking.


Handling: Handling refers to how well a vehicle responds to the driver’s steering, braking, and acceleration inputs.


Inflation Pressure: The amount of air pressure in the tire, measured in pounds per square inch (PSI).

Inner Liner: The innermost layer in tubeless tires that holds air and seals against leaks.


Load Index: A numerical code indicating a tire’s maximum load-carrying capacity.

Load Range: A classification indicating the tire’s maximum load-carrying capacity.

Lug Nuts: Fasteners used to secure the wheel to the hub.

Lug Centric Wheel: Wheels that rely on the lug nuts to center them on the hub.

Lug Studs: The threaded studs on which the lug nuts are fastened.


Mud Terrain Tire: A tire with deep, aggressive tread, and robust sidewall designed to use for challenging off-road conditions.


Negative Camber: When the top of the tire leans inward toward the vehicle.

Nitrogen Inflation: Filling tires with nitrogen instead of air for improved pressure retention.


P-Metric Tires: A system of tire sizing based on millimeters, aspect ratio, and diameter.

Performance Tire: A tire designed for high-speed and handling capabilities.

Plus Sizing: Installing larger diameter wheels with lower profile tires.

Ply Rating: A rating that indicates the tire’s load-carrying capacity.


Radial Tire: A tire in which the cord plies are arranged radially from the center.

Radial Runout: The measurement of the wheel’s deviation from a true circle.

Rim Diameter: The measurement of the wheel’s diameter, usually in inches.

Rolling Resistance: The force required to roll a tire on a surface.

Run-Flat Tire: A tire designed to be driven on for a limited distance after a puncture.


Siping: Thin slits in the tread that improve traction on wet surfaces.

Spare Tire: A smaller, emergency tire carried in the vehicle for temporary use.

Speed Rating: A letter code indicating the maximum safe speed for the tire.

Staggered Fitment: Using larger rear tires than front tires for improved handling.

Steel Belt: Steel reinforcement within the tire’s construction for added strength.

Summer Tire: A tire optimized for warm weather conditions.


Tread: The pattern on the tire’s outer surface that provides traction.

Tread Blocks: The individual sections of the tire’s tread pattern.

Tread Depth: The measurement of the thickness of the tire’s tread.

Tread Pattern: The specific design of the tire’s tread blocks and grooves such as symmetric, asymmetric, and directional tread pattern.

Treadwear Rating: A number that indicates a tire’s expected tread life.

Tubeless Tire: A tire designed to hold air without an inner tube.

Traction Rating: A measurement of a tire’s ability to grip the road surface.


Underinflation: When a tire has less air pressure than recommended.

Uniform Tire Quality Grading (UTQG): A rating system for treadwear, traction, and temperature resistance.


63. Valve Stem: The component used to inflate and deflate the tire.

Vehicle Placard: A label on the vehicle specifying recommended tire pressure.


Wheel Offset: The distance between the wheel’s mounting surface and the wheel’s centerline.

Wheel Spacers: Devices used to create more space between the wheel and the hub.