I have an ancient set of Pirelli P Zero Tyres on my Mk IV which must be 25 years old. They still have good tread, but I would worry about travelling at the national speed limit on them for any distance! I have seen all the Mk IV "hot shoe" drivers are using Avon CR6 ZZs, so I thought I had better join the club. The Pirelli sizes are 275 rear and 225 front, so I was thinking of the same in the Avons with 275/55/15 and 225/65/15s. I see there are also 295 and 245 sizes available. Has anyone tried them, and do they clear the arches OK? My instinct is to stick with the traditional sizes, or am I missing a trick?