Typical, leave your armoured car unattended while you go for a quick leak in the woods, get back and someones nicked not only your tyres, but your wheels and fenders!
Seriously though, what's with the lack of wheels and fenders, is it battle damage? I've seen a few photos of the museum there and the exterior exhibits seem to all be battle damaged, the Churchill had gone over a mine or two and the Sherman's turret was at a funny angle because of a hit