05/31/2011

Tyres and retreading

There is an option for tyres that human beings would be glad to exercise at the end of their modest existence if it was available to them too: retreading. In line with the “new for old” concept, worn-out tyres are turned into reusable new tyres in no time at all –albeit with some restrictions. The precondition for doing this is, however, that the materials used for the tyres are of sufficiently high quality. Although the number of tyres that go through the retread process and are brought back into operation is relatively small, the process is possible nowadays with a few exceptions thanks to advances in chemistry. But that is enough of an introduction: what is the principle behind the retreading of car tyres?

There is a simple basic answer to this question: a machine peels the tread off the tyre and replaces it by new tread. That is all. However: whether a tyre is suitable for retreading depends on many different factors. High-quality retreading is only possible if a check of the tyre in question confirms that there is no damage to the original material. It is a well-known fact that the tyre substructure can be affected badly if the wheel has hit the curb or the car has been driven with tyres at low pressure. Tyres with such histories need to be found and eliminated. Technical facilities are, however, available to distinguish good tyres from bad ones; ultrasonic testing of the substructure can, for example, be carried out to determine any damage.

It is therefore always advisable to drive carefully and to avoid hitting curbs thoughtlessly at speed in an attempt to secure a parking space that happens to be free. Doing this not only protects tyres and saves money; it is also good for the environment and reduces resource input. Because: about 35 litres of oil are consumed in the production of a new tyre, whereas only 5.5 litres are required for the retreading process! Which means that the process helps to minimise the use of valuable resources while saving money for other expenses. Retreads play a minor role, however, accounting for about 3 per cent of the market. There are a number of reasons for this. One explanation is quite simply that retreading is only sensible and justifiable up to the speed category S (up to 180 km/h) or, at most, T (up to 190 km/h).

Retreads are not acceptable for safety reasons in the tyre categories H (up to 210 km/h) or higher – which account for more than 50% of the market for new tyres. Such tyres are attractive even so – because of their low price – and their quality level is at any rate higher than cheap products from China. Retreads hold 40% of the market for lorry tyres in the meantime, on the other hand.