Totally agree with IJM on the Marathon's, but I put them on this week-end on the one bike as it's suppose to be a mix of snow and rain later this week, which usually means ice. The Marathons are awesome on ice and saved me a few times encountering black ice.
But I noticed the back end sliding out too when I would get in that loose thick snow. But given the city's poor plowing it is pretty much impossible to ride if we get over 6 inches anyway so I probably wouldn't attempt it on a regular basis even with a better tire.
But for 75% of the winter the Marathon's did fine and that's what they make trainers for on the other 25%
