I've only ridden 2 or 3 times in the snow on my fixie and it is SO much fun, but only on flat terrain. Just yesterday, started to go down a sorta steep hill when I make a turn and realize the bottom of this path is all covered in snow/ice and I've got no brakes. Luckily I just locked the rear and slid into some bushes. Pretty scary. I've got 23 & 25 on right now and probably going to 32s if the frame can fit them. Slicks not knobbies b/c winters in Boulder are too dry and the knobbies/studs would just wear out faster.