Tires consists of several parts.
Tread: it is the element in contact with the asphalt, ensures traction of the vehicle, resists wear and protects the carcass, is produced with natural or synthetic rubber.
Belt pack or belts and radial belt: multiple layers of steel, nylon, polyester or rayon ropes or threads interposed between the carcass and the tread, which increase the resistance of the tire, stabilize the tread, guaranteeing protection against impacts and punctures and guaranteeing a better distribution of forces on the lateral footprint of the tread and therefore also a greater footprint on the ground, these threads are arranged in the belt at a reduced angle of 15-25 ° and crossed each other, or are arranged at an angle of 0 ° with respect to the median of the tire and possibly also have other belts at different angles for the distribution of forces, in the latter case the belt pack can be replaced by a “radial belt” characterized by a metal wire or by many wires without joints always arranged at 0 °.
Side of the tire or shoulder: protects the plies from atmospheric and chemical agents and also opposes the bending to which it is subjected during use.
Carcass or canvas: allows the transmission of all load forces between the wheel and the ground such as those that are released during braking and steering maneuvers, it also guarantees resistance to inflation and subsequently operating pressure during all maneuvers. This element is mainly composed of Nylon threads placed side by side which can be of different thickness and give greater resistance or smoothness, in fact with the increase in the section of the threads and consequently a decrease in threads per inch, the strength and stiffness of the carcass, but decreasing its smoothness.
Beam ribs or circles: these are steel bands placed in the bead, they accommodate the tire on the rim and keep it in position, preventing it from slipping off.
Filling: generally made of rubber and placed in the heel and side area to allow a gradual transition from the rigid heel area to the flexible side area.
Internal coating: rubber layer inserted inside the tubeless tires, specially designed to prevent air leaks.
Heel or heel groove: layer of rubberised fabric that prevents wear caused by the heel rubbing against the rim edge and that guarantees the necessary friction to prevent rotation on the rim.
Regarding the composition, a tire is mainly composed of natural and synthetic rubber (41%). Natural rubber comes mainly from a tree called Havea Brasiliensis, but other types are also used.
Synthetic rubber is composed of copolymerstyrene-butadiene. A long series of additives are added to the rubber mix, which make it flexible, elastic and resistant to aging. (30%).
The carcass materials - the inner part of the tire - are fabrics and metals and account for 15%. The remaining components account for 14%, which is what we call chemical additives that assist the manufacturing process or help provide greater tire durability.
