What ET are you going to run for a 11.5" width rim? I've seen 11" ET33 and they are borderline from rubbing and this was with a 295. I've seen 305s on a 11" wide rim but they rubbed without some camber changes in the rear.
You are going to want to run a 275 upfront not the 255, you will have 50mm of stagger when OEM was 20mm.
2013 M3 Coupe-MR/BLK ZCP, identical to my 2011.
2011 M3 Coupe-MR/Blk
2007 Porsche 997C2S Speed Yellow/Blk sport seats
2004 BMW M3 Imola/Blk