You should be OK with your proposed tire sizes. Your front offset may require a spacer to clear your KW's but it will be close. The rear offset is pretty aggressive and limits your tire size options. It's too bad you didn't have et27 in the rear and et19 in the front. If so you would have the luxury of running 275/30 & 295/30 tires. A 295 would definitely rub in the rear with your offset.
KW Clubsport 3-way, Akrapovic Evolution, ESS Tune, StopTech Trophy, IND Euro Bumper & Black Mirror Covers, Turner Motorsports Studs/Lugs & Delrin Diff Bushings, MRF Solid Sub-Frame Bushings, RD Sport Sways, Recaro Profi-XL & Planted Seat Brackets, BMW Performance Carbon Fiber Interior Trim, BMW Edition Grills/Gills, Mode Carbon GT4 Splitter & GTS Wing, Advan TC3 (18x9.5/10.5), BBS E05 (18x10/11), G-Force Rivals (275/295)