[racer]

One issue with many summer tires in winter (cold) conditions is that the tire hardens up and doesn't give a very good ride and traction can be worse. Flatspots should work themselves out.

You could always put a few extra pounds of air in to help with flatspotting and or pressure loss. IIRC, each 10 degree drop in temp usually means a 1psi drop in your tires. Assuming no leaks, if you last checked your tires in 70 degree weather and now its 20 degrees, thats a 5 psi drop for your tire.