I had winters on my F10 but non run flat and they did come in handy and were great for stopping in the wet and cold conditions.
I now have a set for my G30 but i have run flats now and as others have said. Peace of mind if you do get a puncture you can stop in a safe place or at least get to your destination before dealing with it.
I have pics and specs on my post i also went down from my summer 19s to 18s . So bought rims and tyres
They did come in handy in the recent weather we have had with snow and ice too
http://g30.bimmerpost.com/forums/sho....php?t=1440456