I have a problem with unusual tyre wear on the rear of my MK4 coupe turbo (had the same problem on a MK4 SRi). The inside of each rear tyre is worn, but it is not smooth like you get with a front wheel tracking problem, it has flat spots all round the inside of the tyre. I have heard it call 50 pencing, because the inside of the tyre is now like a 50p.
I asked the local tyre fitter and they do see it on some cars not just MK4s, but the guy could not really explain what causes it and how to cure the problem.
The car is fitted with a Whiteline rear anti-roll bar. Could this be the cause? Does anybody with a rear ARB have the same problem and does anybody know if there is a way to stop it? Maybe with camber/castor adjustment??