Making tyres is a complex process. Here is a brief guide to how it is done. All pictures are courtesy of Avon Tyres. Thanks chaps.
The first stage is to mix the raw materials which go to make up the tyres. Natural rubber accounts for approximately 40 per cent of the content. Three different types of synthetic rubber are used. Other major components are Carbon Black (durability and colouring), Silica (wet weather grip, reduction in friction) and various chemicals used to fine tune the composition. This is the control unit of the mixer.
The various different types of rubber to be used in the building of the tyres are milled into strips of consistent thickness and width. They are checked for consistency throughout the process. The progress of each batch of rubber is tracked by computer to ensure that the correct blends of rubber are used for each different model of tyre produced and delivered to the appropriate assembly areas in the factory.
The milled sheets of rubber are seen here waiting to be cut to the exact widths and lengths required for tyre construction. Further inspection is carried out at this stage and any imperfections removed.
Tyres are built on a drum. The first sheet is an airtight synthetic rubber, followed by the main casing, the bead and finally several layers of compound and the sidewalls.
Once the layers are completed, the flexible centre of the tyre building drum is expanded which causes the outer surface to assume the profile of the finished tyre.
Green tyres, as they are referred to at this stage of construction, are removed from the building drum and stored ready for the curing process. Note the lack of tread at this point.
For the final part of the process, the tyres are inserted into moulds and cured under pressure at a heat of 170°C. The tyres are cured by chemical reaction. It is at this stage that the treads are formed and the lettering is embossed into the sidewalls. This final part takes around fifteen minutes to complete.
Finally, we can see the tyres on the Dymag wheels. We have opted for a 180/55 rear which we think is plenty big enough. We could go to a 190 but it would slow the steering down too much.