As the only part of a car actually in contact with the road, the tyre is the single most important item when it comes to controlling the vehicle's behaviour.
Instead of an inner tube the tyre has a rubber lining and the pressure of the beading against the rim of the wheel is claimed to give a seal which is proof against any escape of air.
It's been a long and tiring weekend - did music for about 16 hours so far since Friday - but here are a few great links to keep you occupied.
The voice was tired and bored, but not impolite.
But all writer-actors say that until they tire of spending days alone with a computer.
Stage coach travel was rugged and slow, with long distances being an arduous and tiring journey over primitive roads, subject to delay and often impassible in muddy weather.
Add more and you just get grey noise, like the rush of water in your ears when you hold your head under water or the sound of rubber tyres on the concrete roads they sometimes put down to save money.
Remarkably it also offered no wheel spin on violent acceleration, although it would be a different matter in the wet with the road legal track tyres fitted.
The teachers have an important role in the protection of children, but they too live in the same difficult, tiring and often very frightening or humiliating situation.