Postby Saul_Good » Sun Jun 02, 2013 9:14 
			
			
			
			Columbiana,  Assuming your stock wheels are 17x7, 215/45/17 should be a good size that maximizes your 7in width.  
If the offset is right, i think you can get a 17x8 or 17x8.5 wheel and squeeze 245/40/17 on.  I'd triple check with the MS3 forums to be sure tho.  If not, then 17x8 with 225/40/17.
Just be sure to get the proper offset.