Tyres may simply look like a round piece of rubber, but there are many different components that work together to achieve a common goal of delivering the desired performance.
It is the thick layer of rubber compound that comes in direct contact with the road surface. This layer is generally wear resistant that increases the durability of the tyre. Also, it protects other components including belt and carcass from fractures due to harsh road impacts.
Tread comprises of 4 core components namely grooves, lugs, voids, and sipes, determined by the geometrical design of tread pattern. The gap between the rubber patches that runs circumferentially around the tyres is called grooves, and are used in channeling water away from the road. Lugs are the sections of rubber that actually comes in contact with the road. Voids are the spaces between lugs that help the tyre to flex properly, maintain the tyre temperature and displace water. Sipes are the narrow cuts across the tyre tread that help channel water from the grooves to the side of the tyre to reduce the chances of hydroplaning.
Different kind of treads are designed keeping in mind the purpose of the tyre. Performance oriented tyres have bigger contact patches and softer rubber compound because their job is to provide maximum grip. Here, the tyre life is not a priority. Similarly, normal road tyres have more grooves to deal with a vast array of road and temperature conditions, and therefore, flexibility to adapt to different conditions along with a longer tyre life is prioritised here.
Bead is the part of tyre that mounts onto the rim. Proper designing and construction of bead is highly focused upon to prevent any air leakage from tyres. It also ensures that the tyre does not move circumferentialy due to high stress on it. Tyres are designed to fit snugly around the rim even while being deflated to ensure that it does not come off the rim due to sudden loss of air pressure.
Sidewall is the part of a tyre between the bead and the tread where the manufacture specifications and warnings are written. It is a rubber composite reinforced with fibre and steel cord that provides strength and flexibility to carry the entire weight of the car. The height of the sidewall has a great influence on the characteristics of a tyre. A high profile tyre helps to absorb the road irregularities and makes ride comfortable. On the other hand, a low profile tyre is generally used in high performance vehicles as there is less flex which helps maintain maximum contact patch under cornering stress. However, its not able to absorb road bumps making your ride jittery.
Carcass is the internal fibre layer of the tyre that absorbs vibration and sustains load. The carcass needs to be durable enough to sustain stretching and heat throughout the life of a tyre. It also helps in sealing the tyre properly to prevent air leakage.
Belt comprises of metallic cord layer between the tread and the carcass. It provides rigidity and shape to the tyre, and at the same time protects the carcass from cuts or injury of the tread. Many companies have found a way to modulate the belt layout pattern to effect certain parameters. For example, Metzeler M5 motorcycle tyres utilize a technology of modulating the tension of the cord across the circumference of the tyre, so that the cord is under minimum tension at the sides and under maximum stress at the center to prioritise durability while moving straight and grip while cornering.