Along the way, on those hour-long journeys, there is - depending on the traffic on offer - time to think about very ordinary things. "Why is a tire black?" for instance. You have also seen pictures of cars and motorcycles from the Year Kruik that were fitted with (completely) 'white' tires…
As a regular AMK reader you can still remember the report about the Horse Power Run of the Veteran Motors Club in which a lady participated in an old Harley-Davidson with all-white tires ... They were / are made from rubber only. Drive great, but only have a durability of a few hundred kilometers. 'Rubber' wears very quickly.
Soot
It was coincidentally discovered that the addition of soot - derived from petroleum - in rubber triggered a reaction that created another raw material that made tires virtually indestructible. The 'rubber' of a tire consists of more than twenty well-mixed chemicals. The disadvantage of soot, the rolling resistance is high and that costs a lot of energy. "Energy" has everything to do with "environment" and that led to tire manufacturers looking for a friendlier solution.
Silica
And that became 'sand' in a very pure form with the collective name 'silica'. Nowadays all tires are made of rubber and silica (plus about twenty other fabrics) and no longer have to be black. Although Michelin was able to supply 'green' tires a few years ago, it turned out not to be a success because 'black' is simply the (world) 'fashion'. At Vredestein they had a more charming solution for fun. A red or yellow stripe on the side ...
Interesting, these tidbits about tires. I have never known that tire rubber is such a rich mixture. I think it is advantageous for the appearance of a car that the tires are usually black. You don't see dirt very easily.