Tyre Construction and design
There are two main types of tyre construction; cross-ply and radial
Cross-ply tyres refer to the construction whereby nylon cords are crossed diagonally over each other. These are then layered with thick rubber piles providing tough, rigid sidewalls. Whilst cross-ply tyres are tough and provide a higher resistance against sidewall damage, they also have a higher rolling resistance which can cause the tyres to heat up quickly increasing the air pressure within the tyres.
As car designs evolved so did tyre technology and a more flexible tyre was developed known as radial tyres. Radial tyres are constructed from cords which have been rubber bonded and placed so they run across the circumference of the tyre. The radial piles are then covered by a casing belt made up of cord or steel which is then covered by the rubber tread. Radial tyres offer greater comfort, water and heat resistance and improved fuel economy.
Now, let’s look at the individual elements that are added to make up these two tyre construction types.
The tread is the rubber compound which overlays the tyre construction. The tread covers the circumference of the tyre and is the part that makes contact with the road. As such tread patterns are developed for performance in varying driving conditions.
The sidewall is the outer side of the tyre which protects the cord piles. It is made up of rubber compound designed to resist cracking and scuffing. The sidewalls feature information about the tyre such as size, type and brand.
Other sidewall markings include:
- Load and pressure requirement
- Load index
- Speed symbol
- Manufacturing country
- Location of tread wear indicators
- Markings to indicate if the tyre is designed for mud and snow (winter) if applicable
- ECE type approval
- Tubeless / Tube type
Related: Reading a tyre sidewall
The chafer in cross-ply tyres is a lining between the body and the bead (tyre and rim) which prevents them from chafing. In radial tyres the chafer works as added reinforcement strengthening the tyre and converting the forces from the torque.
Found in tubeless tyres, the liner prevents air leaking by covering the inner surface of the tyre.
The bead is a strong, steel cable loop coated in rubber which sits on the rim of the tyre and keeps the tyre in position.
The ply is composed of either nylon piles or steel cord and works to confine the pressure within the tyres. The ply absorbs any braking and steering shocks while driving to provide the motorist with a comfortable ride.
Breaker or belt
Breaker or belt refers to the layer of the tyre between the carcass and the tread. In a cross-ply tyre these are referred to as breakers in a radial tyre this layer is referred to as a belt.
Breakers are constructed of steel wire or nylon while belts can be made up of any number of materials although generally they are also made of steel cord wires. The wires are layered between the tread and the ply.
So you see not all tyres are the same, the research design and technology involved in the manufacturing process is what distinguishes one tyre from another.
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