Many thanks. In my area, the average width of 'speed cushions' is 1,800 - 2,000mm. The average flat area on the tops is 1,200 - 1,300mm, with slopes either side of 350mm - 400mm. The average height is around 80mm. That means that no car in production can straddle speed cushions without the tyres being deformed by the slopes either side of the cushions. I'm trying to set up a test with Bridgestone to determine the effect of speed cushions on different profiles of tyres. That will scientifically determine how many standard size, undamaged speed cushions the different tyres can pass over before damage occurs to their inner shoulders. The TRL did no such test before approving speed cushions. There are no government figures. The only figure I have been able to find is that in 2007, 46 road deaths were directly attributed to tyre failure.