You car looks sweet! Thanks for posting this, it is well timed.
I just ordered a 19" Pirelli winter set up for my 335i.
The logic for it was as I am running 20's the 19" will give a less drastic handling change and I think they are a touch narrower so better in the snow. I am no tire expert, so don't flame me, just passing along what my family friend the tire guy says.
I get more rain and slosh on the West Coast than you do in Ontario and it won't be driven up skiing or anything like that.