I bought studded snow tires when I started commuting to get to work safely in the snow. They are great in the weather, but I've also gone entire winter seasons without needing them. This season I bought non-studded winter tires with the idea of keeping them on the bike all winter. For my climate, they were probably a smarter purchase than the super heavy duty studded tires.

I am looking for suggestions regarding when, temperature wise, to change over to my winter tires. Riding temperatures this time of year are in the 30's, 40's, and 50's. In the past I have ridden regular summer tires down to about 15 degrees F, and they seemed just fine.