Any colour so long as it’s...
Tyres are black because rubber is, right? No. Rubber’s off-white, which is what colour the first car tyres were. They became black when soot was added to try and increase durability. In the early 1900s this changed to carbon black, a low-cost ‘filler’ (created by incomplete combustion of certain materials) that increases strength and grip, and reduces wear. Use a different filler and you can get different colours – you’ll see jazzy pushbike tyres, and Tomahawk sold motorbike tyres in various hues in the early 2000s. The problem is that compatible fillers of another colour are more expensive than carbon black, and they can also compromise the tyre’s characteristics. Not a worry if you’re not after grip, though – Highway Max’s coloured tyres are huge in Australia’s burnout seen.