Tire Introduction

A tire(American English) or tire (British English), is a ring-shaped vehiclecomponent that covers the wheel's rim to protect it and enable better vehicleperformance. The metal tire is basically a flat hoop fitted tightly over theexterior of the wheel. Besides low rolling resistance, its other attributes arestrength, durability, and resistance to wear.

Naturalrubber is the main raw material used in manufacturing tires, although syntheticrubber is also used. In order to develop the proper characteristics ofstrength, resiliency, and wear-resistance, however, the rubber must be treatedwith a variety of chemicals and then heated. The materials of modern pneumatictires are synthetic rubber, natural rubber, fabric and wire, along with carbonblack and other chemical compounds. They consist of a tread and a body. Thetread provides traction while the body provides containment for a quantity ofcompressed air.

Rubber tiresare of two types:

(1) solid,or cushion, tires, in which the rubber portion functions to carry the load,absorb shocks, and resist cutting and abrasion;

Cartire structures:

The mainfeatures of a passenger car tire are the tread, the body with sidewalls, andthe beads. The tread is the raised pattern in contact with the road. The bodysupports the tread and gives the tire its specific shape. The beads arerubber-covered, metal-wire bundles that hold the tire on the wheel.

Inner liner : The inner liner is an extrudedhalobutyl rubber sheet compounded with additives that result in low airpermeability. The inner liner assures that the tire will hold high-pressure airinside, without the air gradually diffusing through the rubber structure.

Body ply : The body ply is a calenderedsheet consisting of one layer of rubber, one layer of reinforcing fabric, and asecond layer of rubber. The earliest textile used was cotton; later materialsinclude rayon , nylon, polyester , and Kevlar . Passenger tires typically haveone or two body plies. Body plies give the tire structure strength. Trucktires, off-road tires, and aircraft tires have progressively more plies. Thefabric cords are highly flexible but relatively inelastic.

Sidewall : Sidewalls are non-reinforcedextruded profiles with additives to give the sides of the tire good abrasionresistance and environmental resistance. Additives used in sidewall compoundsinclude antioxidants and antiozonants. Sidewall extrusions are nonsymmetricaland provide a thick rubber area to enable molding of raised letters andsidewall ornamentation.

Beads : Beads are bands of hightensile -strength steel wire encased in a rubber compound. Bead wire is coatedwith special alloys of bronze or brass. Coatings protect the steel fromcorrosion . Copper in the alloy and sulfur in the rubber cross-link to producecopper sulfide , which improves bonding of the bead to the rubber. Beads areinflexible and inelastic, and provide the mechanical strength to fit the tireto the wheel. Bead rubber includes additives to maximize strength andtoughness.

Apex : The apex is a triangularextruded profile that mates against the bead. The apex provides a cushionbetween the rigid bead and the flexible inner liner and body ply assembly.Alternatively called "filler" .

Belt package :Belts are calendared sheets consisting of a layer of rubber, a layer of closelyspaced steel cords, and a second layer of rubber. The steel cords are orientedradially in radial tire construction, and at opposing angles in bias tireconstruction. Belts give the tire strength and dent resistance while allowingit to remain flexible. Passenger tires are usually made with two or threebelts.

Tread : The tread is a thick extrudedprofile that surrounds the tire carcass. Tread compounds include additives toimpart wear resistance and traction in addition to environmental resistance.Tread compound development is an exercise in compromise, as hard compounds havelong wear characteristics but poor traction whereas soft compounds have goodtraction but poor wear characteristics.

Cushion gum: Many higher-performing tiresinclude an extruded component between the belt package and the tread to isolatethe tread from mechanical wear from the steel belts.