Don't get me wrong, shims are not unsafe, but it will never handle or track properly like it would with a new rear beam. Shims could probably make it better, but like i mentioned before, with tyres at £100 a pop, it could be an expensive long term decission to get it bodged up could cost you a fortune over a year or two. On the plus side, my ibiza which used to drive up the road like a crap (sideways) now drives perfectly.
