Tyres is a black art - pun very much intended. And with the Indian car buyer finally paying some heed to those four black round thingumajigs on his jalopy, making sense out of tyres has never been more important. Not surprising, considering the variables in tyre specs plus the confusing jargon heaped upon unsuspecting motorists from so-called 'experts' in the tyre showrooms.
OVERDRIVE, in association with Goodyear, kicks off a brand new series in which we will try and be educative on the entire tyre business from how a tyre is made and what the numbers on the sidewalls mean, and to help you decide on the type of tyre for yourself besides the right way to inflate tyres.

How Tyres are made
As the figure illustrates, a tyre is made up of several different components.

The Bead Bundle
The bead is a loop of high-strength, steel cable coated with rubber. It gives the tyre the strength it needs to stay seated on the wheel rim and to handle the forces applied by tyre-mounting machines when the tyres are installed on rims.

The Body
The body is made up of several layers of different fabrics, called plies. The most common ply fabric is polyester cord. The cords in a radial tyre run perpendicular to the tread. Some older tyres used diagonal bias tyres - in which the fabric ran at an angle to the tread. The plies are coated with rubber to help them bond with the other components and to seal in the air.

A tyres's strength is often described by the number of plies it has. Most car tyres have two body plies. By comparison, large commercial jetliners often have tyres with 30 or more plies.

The Belts
In steel-belted radial tyres, belts made from steel are used to reinforce the area under the tread. These belts provide puncture resistance and help the tyre stay flat so that it makes the best contact with the road.

Cap Plies
Some tyres have cap plies, an extra layer or two of polyster fabric to hold everything in place. These cap plies are not found on all tyres; they are mostly used on tyres with higher speed ratings to help all the components stay in place at high speeds.

The Sidewall
The sidewall provides lateral stability for the tyre, protects the body plies and helps keep the air from escaping. It may contain additional components to help increase the lateral stability.

The Tread
The tread is made from a mixture of many different kinds of natural and synthetic rubbers. The tread and the sidewalls are extruded and cut to length. The tread is just smooth rubber at this point; it does not have the tread patterns that give the tyre traction.

Assembly
All of these components are assembled in the tyre-bulding machine. This machine ensures that all of the components are in the correct location and then forms the tyre into a shape and size fairly close to its finished dimension.

At this point the tyre has all of its pieces, but it's not held together very tightly, and it doesn't have any markings or tread patterns. This is called a 'green tyre'. The next step is to run the tyre into a curing machine, which functions something like a waffle iron, moulding in all of the markings and traction patterns. The heat also bonds all of the tyre's components together. This is called vulcanising. After a few finishing and inspection procedures, the tyre is ready. 

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