Another BIG reason I switch out in winter (beyond the largest reason of safety) is my set of studded tires cost $890 M&B with studding, and my DWS's cost $1400 M&B. Add that to the fact I can not run chains on a 315/35-20, and the camber DESTROYING wide rear tires and...MASSIVE COST SAVINGS. I also travel to the mountain for skiing a lot, and it seems that when we do get "winter weather" in the Portland area it comes in the form of an ice storm