How a Tyre is Made

How a Tyre is Made To anyone involved in the tyre industry it is a mystery that most drivers have no concept of how their tyre is constructed. It seems odd that, in essence, the tyre manufacturing process today has changed very little in the past 100 years. Messrs Dunlop and Michelin would recognise the processes used today as being very similar to those they used in the early days of the pneumatic tyre. However, it is, despite this, now a much more complex process with many more materials used, and much more science involved in creating the tyre. It can be broken down into the following steps:

1) Mixing

Various grades of natural and synthetic rubber are blended in an internal mixer (commonly known as a Banbury) and mixed with carbon black and a cocktail of other chemical products that enhance the characteristics of the rubbers. This blend is called the "masterbatch" and its make-up is carefully constructed and controlled to ensure the desired performance parameters of the tyre are met with.

2) Calendering

Textile fabric or steel cord is woven to create a complex textile that is then coated with a film of rubber on both sides. Calendered textiles such as rayon, nylon and polyester are used for the casing and the cap plies. Steel cord is used for the belts.

3) Tread and Sidewall Extrusion

The tread and sidewalls are constructed by forming two (or more) different and specifically designed compounds into profiles by feeding the rubber through an extruder. Extruders produce continuous lengths of tread rubber, or sidewall rubber, which are then cooled and cut to specific lengths.

4) Bead Construction

The bead core is constructed by coating plated steel wires, which are wound on a bead former by a given number of turns to provide a specific diameter and strength for a particular tyre.

5) Tyre Building

Tyre building is traditionally a two-stage process. Although modern tyre factories now use a certain number of single-stage building machines, two-stage building is still widely used, particularly for the more standard sizes. In the first stage, the innerliner, the body plies and the sidewalls are placed on a building drum. The beads are then positioned, the ply edges are turned around the bead core and the sidewalls are simultaneously moved into position. In the second tyre building stage, the tyre is shaped by inflation, with two belts, a cap ply and the tread belt being added. At the end of this stage the tyre is now known as a "green tyre". The "green tyre" has no tread pattern, no markings. It is simply a bare rubber casing.

6) Curing

The green tyre is now placed in a mould inside a curing press and cured for a specific length of time at a specific pressure and temperature. Each curing press is equipped with an interchangeable set of moulds, but will only press one tyre, or one size and pattern at a time. The finished tyre is then ejected from the mould.

7) Trimming

Excess rubber is removed from the cured tyre on a trimming machine.

8) Inspection

Before the tyre is allowed to go to the despatch warehouse, it is inspected both visually and electronically for quality and uniformity.