From the archives of Bob Montgomery, motoring historian
SOOT, SULPHUR AND RUBBER! In case you didn't already know, rubber got its name because an 18th century scientist and theologian, Joseph Priestly, discovered that it would remove pencil marks better than stale breadcrumbs. Before that, Colombus had taken samples of rubber back from the New World to Queen Isabella, but it was some three centuries before rubber was rendered stable.
The biggest breakthrough in rubber technology came with the discovery of vulcanisation by Charles Goodyear in 1839. Goodyear had a thing about rubber: he wore rubber shoes, a rubber coat and carried a rubber wallet. Prior to his discovery, rubber was unpleasantly sticky when warm, and had a glass-like brittleness when cold.
Goodyear discovered (quite by accident) that when sulphur was added to rubber and heated, it produced a compound that was very tough and resilient. Shaped like dough before vulcanisation, afterwards, it would have a certain amount of elasticity but would always spring back into shape.
It was an Englishman, Robert William Thompson, who invented the pneumatic tyre in 1845 and, although he obtained a patent for his invention, John Boyd Dunlop independently re-invented the pneumatic tyre in 1888. But even with vulcanisation, rubber was not strong enough on its own to take the sort of treatment to which a car tyre is subjected.
As a result, tyres were reinforced with various layers of fabric. John Dunlop used Irish linen, in America cotton duck was used, and for a long time in the early days of car tyre manufacture there was a debate about the relative merits of Sea Island cotton and Egyptian cotton.
Incidentally, another element in the construction of car tyres is carbon black - another name for soot! Added to rubber it adds toughness and strength while at the same time turning the rubber the black that we have come to expect.
It may seem curious, but the idea of adding a tread did not at first occur to early tyre makers. I was taught that the rubber by itself provided sufficient friction and early tyres were completely smooth.
But motorists wanted to protect their expensive pneumatic tyres from punctures, and began to fit various protectors on to the tyre. Some of these claimed to protect against skidding as well as punctures and blow-outs while also supposedly prolonging the life of the tyre. Leather covers for tyres were available from several manufacturers, some fitted with metal studs. (One Canadian firm even went so far as to manufacture a complete tyre made of leather).
It was the development of 'non-skid' tyres that led to the development of tread patterns. It has to be said that at first this was merely a marketing gimmick. Firestone, for example, produced a tyre which had as its pattern the words 'NON SKID' repeated again and again. Another manufacturer produced a tyre with hundreds of little suction cups rather like the arm of an octopus.
In all, thousands of tread patterns were registered and each became the distinctive pattern of a particular tyre manufacturer. By 1920 in the US alone there were some 500 tyre tread patterns registered, including cloverleafs and even one design based on a Navajo rug.
As so often, it was racing that provided the spur to progress, and tyre patterns which did aid adhesion were developed for the race tracks, so that in time these patterns found their way on to road tyres. Today, it's hard to imagine a product that has developed so much since its origins as the high-tech motor tyres which we take so much for granted.