Went through this decision 2 years ago, ageee with everyone else, 18s - No Way, 17s - pushing it, but can be done, 16s - probably best. I went with 16s and 205/50, and very satisfied. I'm picking up some Eibach pro-kits to close the gap,but don't want it slammed.

Have you looked at Neuspeed's sof-Sport, they're only supppose to drop you about .75", which may not be enough with 17s, but would ensure no rub.