Dave 5mm from new, i don't bother using them on the road. Should last about 4 - 6 trackdays depending on how you drive.

A freind of mine was in a 4x4 saph stage 1 with R888 & he was quicker than his mate in a evo 6 tommy makinen with road tyres, the evo was holding him up once the road tyres started to overheat he was sliding on every corner, that was at Lydden.

Simon.