In general the tyres are at their most efficient when on the point of losing traction.? On tarmac, you will get the maximum braking performance out of a tyre when it is on the point of locking the wheel.? If you brake any harder the wheels will start to lock which, on tarmac, will reduce your braking performance.? Similarly, if you release the brake slightly, you will be braking slightly less.? Duh!

In the same way as braking, you will gain maximum acceleration out of the tyres on tarmac when they are at the point of losing traction (just about to slip or spin).? Whilst wheel spins are a laugh and a good way of getting attention from 12 year olds, it is usually reducing your acceleration performance.

There are a couple of extra aspects to accelerating, however, which mean that it is probably better to have some controlled wheel spin than to not spin the wheels at all.