Why spend all the money on winter rubber then stick them on a ridiculous looking set of steelies? I'm all for function over form, but a set of half-decent (or OEM 2nd hand) alloys aren't that expensive.
My winters live on the car from mid-Nov til mid-March - 4 months. I don't want to be driving around on steels for a third of the car's life. I was originally searching for 17" as the perfect balance between form and cost, but ended up on 18"s simply because the alloys were very cheap.
It's gone - no longer an e90 330i owner