How much rubber is in a tyre?
Very little. The ‘rubber’ you see on modern big bike tyres is made of synthetic polymers, silica (silicon dioxide), and/or carbon black (a sort of soot), though some have a bit of natural rubber in the sidewalls. ‘Silica and carbon black are fillers,’ says Michelin’s motorcycle technical chief Tony Charlton. Fillers form bonds that glue the tyres together. ‘The beauty of carbon black is the amount of dry grip it generates,’ says Tony. ‘Silica performs well at lower temperatures, so it’s good for a quicker warm-up, and gives very good grip in the wet. Sports touring tyres like our Road 5 use silica compounds and no carbon black. Our race slicks are all carbon black, while the dual compound road sports tyres will be a mix – silica in the middle, carbon black round the edge.’