Basically carbon black is added to rubber to give it more abrasion resistence. The wearing off tyre is reduced to large extent by adding carbon.
The coloured tyres are also coming in which carbon is replaced by precipitated silica which is in white colour and give same abrasion resistence as carbon but mix with difficulty with rubber.

Pigments can be added to make tyre of desired colour which is future trend to give sexier look to automobiles