MJR:
A compromise on wheel colour for your white car would be anthracite. Yes, 18" would be better than 17" in the looks department, but for practicality 17" on our broken tarmac would hold sway both for the improved ride quality and safety from kerbing.
I've got 18" Monza Shadows on mine and I am for ever in a worried state in case I kerb them. Hence it is prudent to choose tyres with good rim protection.
Rim protection on Bridgestones 5.5 mm, on Continentals 5 mm, on Goodyears and Michelins 4.5 mm. The rest of the tyres around are pretty useless in this respect.
Best of luck in your search.
