Darra Tyres, Brisbane

Making a tyre is a lot like baking bread.

That humble black piece of firm but soft rubber stuff that touches the pavement and allows you to drive a high speeds, turn corners safely, stop on a dime is actually quite a marvellous piece of technology.

There are perhaps 200 different ingredients that go into making each tyre. Some of major ingredients are:

1) Activators: Zinc oxide, stearic acid.
2) Antidegradants: Para-phenylenediamine.
3) Curatives: Sulfur, sulfemamides.
4) Fillers: Carbon black, silica, clay, titanium oxide.
5) Polymers: SBR, EPDM, polybutadine,
6) Softeners: Hydrocarbon oil, resins.

The actual amounts of each ingredient will change with each tyre brand and purpose of the tyre e racing versus earthmoving versus driving the kids to school. When someone does a burn-out and leaves skid marks, you will notice that it’s a long strip of black. You are seeing the component called ‘carbon black’.

Tyre Construction

• The bead is a loop of high-strength steel cable coated with rubber. It gives the tyre the strength it needs to stay on the wheel rim and to handle the forces such as turning and load bearing.

• 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 tire run perpendicular to the tread. The plies are coated with rubber to help them bond with the other components and to seal in the air.

A tyre’s strength is often described by the number of plies it has. Most car tires have two body plies. Whereas large commercial jetliners often have tires with 30 or more plies.

• 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 tire stay flat so that it makes the best contact with the road.

• The sidewall provides lateral stability for the tire, protects the body plies and helps keep the air from escaping. It may contain additional components to help increase the lateral stability. Run flat tyres will have additional reinforcing as they are designed to be driving at low speeds when flat.

• 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.

Assembling the tyre

All of these components are assembled in the tyre binding 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 dimensions.

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 through a curing machine, which moulds in all of the markings and traction patterns. The heat also bonds all of the tyre’s components together. This is called vulcanizing. After some inspection procedures for quality and control purposes the tyre is finished.