In general, fillers are added to the rubber. These fillers can be carbon black, silica, carbon or chalk. They bind the rubber and make it more resistant to wear, as rubber on its own can crumble, particularly as a result of breaking. We use fillers to counter this effect and increase the mileage of your tyres. However, this can harden the rubber compound a little.
Fillers are also the reason for the colour of tyres. Carbon black was the first filler to be used and gave the tyres their colour. However, coloured tyres never made their breakthrough, even when other fillers and therefore other colours came into play later on. That is why tyres are still black to this day.
In contrast to the early days, we use silica in the compound for modern tyre manufacturing. Silica is the name given to silicic acid salt. This substance binds the rubber particularly well with the sulphur, which is essential for the vulcanisation of the tyres later on. During this process, the tyre material is heated to combine the chemical bonds of the individual substances to create elastic rubber. This allows us to provide good mileage without having to sacrifice other properties.