I just got a pair of Schwalbe Marathon Winters in 700 x 40 and put them on my Plan B hybrid that I have been using as a winter bike. I had been riding with hybrid 700 x 28 tires which were fine for the occasional slippery patch, but the roads for the past couple of weeks have been solid snow pack and/or ice. I haven't seen pavement except in the lane tracks for quite a while. Big difference, I took a short ride to try them out as, by the time I got home from work it was already getting close to dark. I did about a half hour on residential streets at 10-12 mph with lots of stops and turns and was very pleased. I never even felt close to breaking traction. Even when I went through some rough stuff on purpose, the control was excellent. When I have more time (tomorrow I hope) I'll take them out for a real test, but even if all I do is tool around at 12-15 mph its a whole lot better than staying indoors.