There are few things in life that people don't question. One is why wheels are round (a topic for another week if you're unlucky) and another is that tyres are black - but why?

Most people think of tyres as black rubber but it's not the rubber that makes them black - carbon black powder is the critical ingredient that not just gives the colour but also provides the structural strength that tyres need - both on the road and the race track.

A tyre typically contains around 30% of carbon black which is one of the most critical ingredients in tyre construction. Simply, it is manufactured by burning crude oil and manufacturers around the world offer ever-improving qualities.

The burning process produces 'grains'. These are round but the best quality is when the grains resemble meteorites and have a larger surface area. Dunlop continually assesses the carbon black on offer to get the best product for each application.

All tyres contain an element of carbon black but it is now possible to produce coloured tyres by using a high proportion of a silica compound that can be pigmented to produce the required colour. This doesn't have the strength properties that a higher level of carbon black affords but can have useful applications such as promotional activities.

Unlike the response to Henry Ford's 'any colour so long as it's black', tyre producers are not looking to provide high volumes of alternatives - so black and round is here to stay.