yeah, i take it you want 185/55 to maintain the correct rolling radius? You might have problems with tyres that big and major lowerage. 165/60 is a safer bet but what I use would be better still. Ive got no problems with scrubbage, although Im only lowered about 60/50
the ATS cups are et33, so stick out a bit more than the steelies would. They sit really far in at the back, but sit perfectly at the front. heres a pic my mate took of it at all types
adam is right, most of the time people that go for 70mm down put wide 13s on and 175/50 tyres (speedo even more out!)