Tire Terminology

Do you feel like your auto mechanic is speaking a different language when they talk about tires? We have provided the tire terminology below to help you understand how your tires are constructed and to help you make informed decisions about your vehicle.

Tire Construction

Tire Diagram

Bead Bundle: The Tire Bead Bundles secure the tire to the wheel. They are large mono-filament steel cords that are wound together to form a cable or ribbon-type configuration.

Bead Filler: The Bead Filler is a rubber compound that is incorporated within the bead configuration and extends up into the sidewall area.

Body Piles: Where the tire sits against the edges of the wheel, creating a seal that holds air in the tire is called the bead.

Carcass: The layer above the inner liner, consisting of thin textile fiber cords bonded into the rubber. Largely determining the strength of the tire and helping it to resist pressure. Standard tires contain about 1,400 cords, each one of which can resist a force of 33 lb.

Undertread: Material between the bottom of the tread rubber and the top layer of steel belts; acts as a cushion that enhances comfort.

Sipes: Special slits within a tread block that open as the tire rolls into the contact patch and then close, breaking water tension on the road surface and putting rubber in contact with the road.

Tread: Provides traction and turning grip for the tire and is designed to resist wear, abrasion, and heat.

Ribs: A pattern of tread features aligned around the circumference of the tire. Usually, there are multiple ribs across the tread area of a tire.

Shoulder: The area of the tire where the tread and sidewall meet.

Sidewall: The Sidewall protects the side of the tire from impact with curbs and the road. Important details like the tire size and speed rating are written on the sidewall.

Bead Chafer: Protects the body plies against abrasion from the steel bead wires and helps to stiffen the bead area of the tire.

Cap Piles: This is located above the steel belts and towards the tread.

Belts: Also known as Crown Plies, these provide the rigid base for the tread.

Grooving: The Space between two adjacent tread ribs; also called tread grooves.

Inner Liner: An airtight layer of synthetic rubber (similar function as an inner tube)

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