I've always assumed that the law says that tyre repairs must meet BS159F and therefore Z or W rated tyres cannot legally be repaired. This seems logical and makes sense. Whether it's overkill or not is another issue. However, surely the temporary repairs the RAC et al offer are also illegal since they cannot possibly meet BS159F. Surely you're not allowed to drive a temporarily unroadworthy vehicle? So could it be that BS159F is a guideline for the industry rather than law? I'm beginning to wonder if the whole BS159F thing is an excuse to sell more tyres.