[...] cheat - and buy 4 x grey carpet tiles from B&Q and put those where the tyres sit.
Thanks for the tip Nick and Stuart - an excellent idea. Yes, I remember the powdery stuff, which I tried to clean off as much as possible.
The paint was Screwfix 'No Nonsense Trade Floor Paint'.
Perhaps I should do a pair of tram lines so that I can fill in later with a full floor of fetching grey !
