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For safety on the road, the tyre is the
most important part in the vehicle

The tyres are influenced by the propulsion-, the braking- and the suspension. The tyre has to transfer all these things to the road, i.e. all the other systems are dependent on the them as well. To be able to concentrate fully on it's job, over the years the tyre has been relieved of a number of it's duties. Thus, it's resilience capacity is now only very limited. It has to concentrate fully on the job in hand. In addition, the combination of tyre and road surface has become a major source of noise e.g., on the motorways. Without compromising somewhere, speed, comfort and safety are probably not possible. Depending on the requirements, the tyre is balanced accordingly.

The tyre business is difficult.

Apart from good traction and a low noise factor, car drivers also want affordable durability, good tyres are not cheap. In America (depending on how you drive?), a certain mileage performance is even guaranteed. Because of the almost unlimited amount of tyre-sizes, the storage of tyres, by a tyre dealer, is no longer possible. Added to this dilemma, there are also more and more old-timers around.

Rubber, soot and a Rayon/steel-cord combination

Originally, tyres were produced completely from natural rubber. At that time they were much lighter in colour. They only became black after soot became available as an active filler. Nowadays, they can be made up from over 200 different materials. The decisive firmness is provided by the steel wires (steel-cord). In the pre-production the wires are possibly twisted and given a brass casing, then under low humidity conditions, are vulcanized into the rubber mixture and applied in layers. With the exception of certain low rolling-resistance tyres, all car-tyres are fitted with steel bands in the tread, whereby, in the side-walls only rayon (nylon material) provides the firmness. This runs through the tyre, from bead to bead. In trucks, steel-cord is used. The beading has always been reinforced with a high tensile wire.

Natural-/synthetic rubber and softeners for durability

Apart from the reinforcing material, the rubber mixture is decisive. One third of the tyre is natural rubber, this is supplemented by some synthetically produced material, which still does not quite have the qualities of the natural product. Chemical substances are added which, e.g., serve to bind and to prevent air and moisture from entering. The former inner-tube has been replaced by the 'inliner' (rubber lining on the inside surface of the tyre) to improve the sealing. The softeners are very important. Their importance can be seen, when after a few years and only little use, cracks appear in the side-walls. For this reason, tyres should be changed, at the latest, after 8 years.

Worn out tyres, either retreaded or
processed into a granulate material

In Europe, in the meantime, used tyres may no longer end up on a dump. Of the 75 million in Germany alone, approx. 30% are retreaded. The rest are chopped up by enormous spiked rollers to 20 cm pieces, then later further reduced to approx 5 cm granules. The aim is, first of all, to remove the steel portion (20% of the weight) using magnets. After a further reduction process, even the textile portion can be drawn out. This is then converted into industrially used heat, while the rubber granulate can then be used for matting, coverings for slipping prevention or sound absorbtion and, e.g., as protection against injuriries in playgrounds.

A warning to drivers: Servicing is important!

The inspection consists of a visual examination, which may on no account, be questioned. For this reason there is the Tread Ware Indicator, an additional marking on the edge of the tread which is found in all relevant tread-series. This is raised 1.6 mm above the tread-base. Should this indicator be worn away, the changing of the respective tyre is urgently recommended. One point which is almost more important, is the overall monitoring of the tyres. To find out more, please read this. 09/11