... on my Cupra R with chassis KW II Inox (hard set) I have BBS CH-R 8.5x19, ET 48, tyre 235/35/19 Bridgestone Potenza RE055A and on front are problem with arch-liner sometimes.
Size 8.5x19 ET 43 in front is best for reduction, rear 8.5x19 ET 40 by both with tyries 235/35/R19, my opinion.
The lower the ET, the more the wheel sits out. So ET 40 will definitely touch on a lowered car because it will sit more outward.