I did a web search on this topic a while ago, but no one specifically stated that lower pressure should be used for winter tires. So I just still set mine close to 35 psi a few weeks ago, when it was still warm. I figured that it will lose a few pound when it gets below freezing. By the way, mine tires are Michelin X-ICE, same size as yours, and they looked quite flat even at 35 psi (not more inflated compared to 20 psi).
