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

Natural rubber is the main raw material used in manufacturing tires, although synthetic rubber is also used. In order to develop the proper characteristics of strength, resiliency, and wear-resistance, however, the rubber must be treated with a variety of chemicals and then heated. The materials of modern pneumatic tires are synthetic rubber, natural rubber, fabric and wire, along with carbon black and other chemical compounds. They consist of a tread and a body. The tread provides traction while the body provides containment for a quantity of compressed air.

Rubber tires are 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; and (2) pneumatic tires, in which the load is carried and the shocks are absorbed mainly by the compressed air that fills the tire. Pneumatic tires are now used for almost all free-moving vehicles because of their greater cushioning ability and other advantages. Solid rubber tires are now used only on industrial and farm carts and on military vehicles, applications where tires are liable to be cut or pierced.

Car tire structures:

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

• Inner liner : The inner liner is an extruded halobutyl rubber sheet compounded with additives that result in low air permeability. The inner liner assures that the tire will hold high-pressure air inside, without the air gradually diffusing through the rubber structure.
• Body ply : The body ply is a calendered sheet consisting of one layer of rubber, one layer of reinforcing fabric, and a second layer of rubber. The earliest textile used was cotton; later materials include rayon , nylon, polyester , and Kevlar . Passenger tires typically have one or two body plies. Body plies give the tire structure strength. Truck tires, off-road tires, and aircraft tires have progressively more plies. The fabric cords are highly flexible but relatively inelastic.
• Sidewall : Sidewalls are non-reinforced extruded profiles with additives to give the sides of the tire good abrasion resistance and environmental resistance. Additives used in sidewall compounds include antioxidants and antiozonants. Sidewall extrusions are nonsymmetrical and provide a thick rubber area to enable molding of raised letters and sidewall ornamentation.
• Beads : Beads are bands of high tensile -strength steel wire encased in a rubber compound. Bead wire is coated with special alloys of bronze or brass. Coatings protect the steel from corrosion . Copper in the alloy and sulfur in the rubber cross-link to produce copper sulfide , which improves bonding of the bead to the rubber. Beads are inflexible and inelastic, and provide the mechanical strength to fit the tire to the wheel. Bead rubber includes additives to maximize strength and toughness.
• Apex : The apex is a triangular extruded profile that mates against the bead. The apex provides a cushion between 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 closely spaced steel cords, and a second layer of rubber. The steel cords are oriented radially in radial tire construction, and at opposing angles in bias tire construction. Belts give the tire strength and dent resistance while allowing it to remain flexible. Passenger tires are usually made with two or three belts.
• Tread : The tread is a thick extruded profile that surrounds the tire carcass. Tread compounds include additives to impart wear resistance and traction in addition to environmental resistance. Tread compound development is an exercise in compromise, as hard compounds have long wear characteristics but poor traction whereas soft compounds have good traction but poor wear characteristics.
• Cushion gum : Many higher-performing tires include an extruded component between the belt package and the tread to isolate the tread from mechanical wear from the steel belts.
• Other components : Tire construction methods vary somewhat in the number and type of components, as well as the compound formulations for each component, according to the tire use and price point. Tire makers continuously introduce new materials and construction methods in order to achieve higher performance at lower cost.