I'm running 15" steelies so there may not be many people that have experienced the same as me but here goes! I've just lost my second front tyre due to the hub-caps moving and tearing the tyre valve. First time it happened was at the Nurburgring in Germany, on the nearside. Fortunately I managed to pump some more air into the tyre and keep it inflated enough to drive it to a garage and have a new valve fitted. I then removed the plastic hub caps. When I got the car back after it's MoT, just before Xmas, the garage had put the hub caps back on and I didn't really think much of it at the time.
Anyway, my flatmate was driving the car home on Sunday night and the offside valve has now been split by the hub cap moving round. He didn't have a phone on him so tried to just nurse the car back. The tyre has come off the rim and is now trash. So is this a known design flaw with VX hub-caps?? I guess most people have alloys so it's not an issue. I had new valves fitted when I had all 4 tyres replaced back in May. Perhaps they are poor quality valves or perhaps designed for alloys? I don't know really. All I do know is that I not putting the bloody plastic hub-caps back on!