Excessive tyre wear under braking.

[OwenP]

During an incident I heard about recently a car slamed into a van at high speed (the van was stopped) upon investigation the car was braking for probably 40 ish yards and had reduced part of his tyre down to the steel banding.

Anyone feel like estimating the speed required to do this given that the car impact speed was thought to be between 70-100mph and the van was a shortwheel based car body type that was thrown clear over a ten foot fence and travelled about 20 yards from the scene.

Somehow the van driver survived apparently without anything more than bruises. Not so sure on the condition of the car driver.

[Homer]

During an incident I heard about recently a car slamed into a van at high speed (the van was stopped) upon investigation the car was braking for probably 40 ish yards and had reduced part of his tyre down to the steel banding.

So you mean the wheels locked up.

It (the question about excessive wear) would depend on too many factors. The ammount of tread depth initially for starters.

As for the speed before braking.

A rough estimate, 40 yards at 0.9g braking with a final speed of 70mph would suggest an initial speed of 90mph.

If the impact speed was 100mph then the initial speed was a little more than 110.

0.9g is probably on the high side, depending on conditions the initial speed could have been considerably lower.

So given the vagueness of the impact speed (70 to 100) I can only suggest somewhere between 80 and 110.

[Kowalski]

Formula one cars have very soft tyres, they can put a flat spot on the tyre braking but its fairly rare for them to wear a tyre down to the canvas. An F1 car is 600kgs BUT it has another 2 tonnes of downforce, so car tyres have LESS load on them, travel more slowly. Car tyres are made of much harder rubber than F1 tyres, an F1 car uses 3 sets of tyres in a 200 mile race, I get 40k miles out of a set of tyres. I refuse to believe that 40 yards of braking would wear a legal tyre down to the steel unless it was pretty much bald to begin with. I've locked tyres on cars before and not put noticeable flatspots on them.