Well I've now solved the problem for my S8!
Today I acquired (at maybe a bit over the odds) an "average" (few light scratches) full set of 5 17" * 7.5J Avus wheels that I'm told originated on a 2002 S4.
Just got to decide on tyres and how many (probably only 4) and get them ordered and fitted. Oh, and tidy up the wheels a bit first.
I'm going to TRY and see if I can get them on without SWMBO even noticing.
I suspect that the subtlety of 18" vs 17" of the same design with deeper tyres will pass her by....
