A lot of materials are used to produce tires though rubber is a main material used. These materials are combined with rubber compounds in the different composition that make up the tire's construction.
2-2) Casing(Ply)
The casing is the framework of the tire. It must be strong enough to hold high pressure air, yet flexible enough to absorb load changes and impact. It consists of plies (layers) of tire cords (sheets of parallel strands of a strong material) bonded together with rubber. The cords in bus and truck tires are generally made of nylon or steel, while in passenger car tires the cords are generally made of polyester, rayon or nylon cords. Tires are generally classified into radial and bias ply types, according to the direction of the casing cords.
2-3) Tread
The tread is an external rubber layer protecting the casing from wear and external damage caused by the road surface. It is the part that directly contacts the road and generates the frictional resistance which transmits the vehicle's driving, braking and cornering forces to the road. The tread pattern, which consists of grooves molded into the tread surface, is designed to help the tire transmit these forces to the road more effectively depending on the road surface.
2-4) Sidewalls
The sidewalls are rubber layers which cover the sides of the tire. They continuously flex under the loads applied during travel and protect the casing from external damage. The sidewalls bear the "manufacturer's name, tire size and other important information and warnings.
2-5) Breakers (Belts)
These are the angled cord layers running beneath the tread in radial ply tires. They provide good handling properties and improve tread life. Steel cords are mainly used as the belt material.
2-6) Beads
The free edges (or sides) of the plies are wound around strong steel bead wires. This prevents the tire from being thrown off the rim by the various forces acting on it. The pressurized air inside of the tire forces the beads out against the rim of the wheel and holds them securely in place. Hard rubber chafer strips protect the beads from damage which might be caused by chafing against the rim by hard rubber chafer strips.
2-7) Inner liner
An inner liner is incorporated in the construction of tubeless tires. It consists of a layer of rubber on the inside of the casing. Its purpose is to provide a complete seal which retains the internal inflation pressure.
