60mph to 0 in a mbuttive cloud of smoke

During my time in the police I underwent an accident investigation course. One way to work out how fast a car was going prior to an accident is to 'work back' from the length of skid marks left on the road surface. In order to do that you have to determine the 'co-efficient of friction' of the road surface at the place of the accident. The method of doing this was to drive a police vehicle up to the point of the accident and then lock the wheels up at a pre-determined speed. You then measure the skid marks you have left and using a calculation you can determine how fast the accident car was going. All a bit long winded - but police traffic cars were put through this test exercise fairly frequently without any serious problems with the tyres. The Force I worked for had a car that was used for this skid testing during accident investigation courses at an old airfield. I queried how long the tyres lasted put to this punishment and was told that they lasted very well. I don't think you have anything to worry about! How they work out co-efficent of friction today when most cars have anti-lock brakes I don't know! (But then if there's no skid marks at the scene of the accident then there's no point to the exercise anyway!!).

Kev