What is the purpose of a carbon insert?

On the tread of some tires, a thin strip of rubber of a different color is easily noticeable. Of course, this gives rise to a lot of speculation and ideas about defects or chipped tires, but the matter, of course, is not in this. Everything is explained much simpler.

With the advent of energy-saving tires, the recipe for the rubber mixture of tires has undergone significant changes, because more and more silicon or, as it is commonly called, "silica" has appeared in the tire to reduce rolling resistance. In part, this has led to a reduction in the content of soot, or, in technical language, "technical carbon", and it, in turn, has good electrical conductivity among all its useful properties. Thus, tires diverted the accumulated electric charge naturally, through the tires. But the trend towards energy consumption gradually began to change the ratio of technical carbon and silicon in the tire, and the diversion of static electricity became more complicated.

Engineers easily and elegantly solved this problem by simply adding a special insert with a high carbon content to the tread, which is considered an excellent conductor. It is logical to assume that the size of the carbon insert can directly indicate how energy-efficient it is, because the more insert in the tire, the more silicon in the tire, and the less fuel it consumes. But this cannot be stated for certain, because the rubber compounds of modern tires are too complex and such simple signs are not always unambiguous.