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TIRE CONSTRUCTION

A radial tire is built from six main parts, and knowing what each does explains why some damage is repairable and some is not. The tread grips and resists wear. The carcass ply cords determine strength. The belts stabilize the tread. The beads clamp against the rim for an airtight fit. The sidewall absorbs impacts from curbs and rocks and carries all the printed specs.
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INNER LINER

The days of tubed tires are over. Today's modern tires utilize synthetic rubber instead—specifically butyl rubber*—which is virtually impenetrable to water and air.
However, over time, there will be slight air loss, so check your pressure every month.

CROWN PLIES (OR BELTS)

Crown plies provide the rigid base for the tread.

TREAD

The tread provides traction and cornering grip for the tire and is designed to resist wear, abrasion and heat.

CARCASS PLY

The carcass ply is the layer above the inner liner and consists of thin textile fiber cords (or cables) bonded into the rubber.

These cables are largely responsible for determining the strength of the tire.

BEADS

The beads clamp firmly against the tire's rim to ensure an airtight fit and keep the tire properly seated on the rim.

SIDEWALL

The sidewall protects the side of the tire from impacts with curbs and the road.
This is where the important details about the tire can be found, such as tire width and speed rating.

Frequently asked questions

BFGoodrich answers your most asked questions.

FAQ

Six main components. The inner liner holds the air. The carcass ply is textile fibre cords bonded into rubber and is largely responsible for the tire's strength. The beads clamp firmly against the rim to keep the tire seated and airtight. The belts stabilize the tread area. The sidewall protects against impacts and carries the printed information. The tread provides traction and cornering grip while resisting wear, abrasion, and heat.

A radial tire is one where the carcass ply cords run directly across from one side of the tire to the other, radiating out from the centre, with stabilizing belts underneath the tread. Almost every tire on the road today is radial. It separates the flexible sidewall from the stable tread, which improves grip, ride comfort, and tread life over older bias construction.

The belts sit between the carcass ply and the tread, usually made of steel cord in modern radial tires. They stabilize the tread area so it stays flat against the road rather than squirming under load, which improves handling precision, tread wear, and puncture resistance. Belt separation is one of the failure modes that makes a tire unrepairable.

The sidewall flexes with every rotation, thousands of times per hundred kilometres. Any patch or plug bonded to a surface under that much repeated flexing eventually separates, and when it fails it fails suddenly. That is why a cut through the sidewall cords, a bulge, or a sidewall puncture means replacement regardless of how small it looks.

The sidewall is the area between the tread shoulder and the rim bead, the vertical face you see when the tire is mounted. It carries all the printed information: brand, tire line, size code, load index, speed rating, DOT date code, and any 3PMSF or M+S winter markings.

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