The 18" 397s and 405Ms are what I run (405Ms for my summer wheels and 397s for my winter wheels)
IIRC these are the dedicated winter wheel options for all F3x cars; and would run 225/45/18 tyres all round for RWD and xDrive
My F31 is RWD, so I run 235/45/18s all round as they offer a straighter sidewall/better rim protection etc - but no good with xDrive IIRC
If you want 400Ms, you just need x4 18x8s (ie x4 front wheels)
To give you an idea:
Summer 405Ms:
Winter 397s:
