Tread
It is the area that contacts the road. Since it is a thick rubber layer, it protects the inside carcass against impact and external damage, while extending the tire life. It also performs various functions such as balancing braking force and driving force, and drainage through the tread pattern on the tire surface.
Side wall
It is the side part of a tire, the part between the shoulder and bead. It protects the carcass and ply cords from moisture penetration or friction, while bearing repeated bending and stretching (extension and contraction) while driving. Various information is indicated on the sidewall of a tire such as brand name, size, date of manufacture, safety indication, and Treadwear Index (TI).
Carcass
Carcass is the frame of a tire. Since it supports the strong air pressure, it must be strong, and at the same time, flexible enough to absorb the load changes and external impact. Carcass is composed of the cords that are wrapped with rubber. In general, a tire is classified into a radial and bias tire depending on the direction of the ply. The cord for a bus and truck is made of nylon and steel in general while polyester, rayon, or nylon code is used for the car tires.
Belt
It is a powerful reinforced layer that is introduced to the circumference direction between the tread and carcass in radial tires. It serves the role of a shock absorber, and particularly, it secures steering performance and stability, and increases the elasticity of the tread by firmly holding the carcass.
Bead
It is the part where a tire and rim meet. At the center, there is a ring-shaped bead wire made of steel, which covers the end of the carcass. It sets the high-pressured air to the wide tire and rim and especially, the bead part of the tubeless tire plays significant role in maintenance of the air-pressure.
Inner liner
The rubber layer of a non-tube type tire is specially made to prevent air release. The inner liner of a non-tube type tire serves the identical role as the inner tube of a tube-type tire.