Pynchonite

Hello!
I thought it would be helpful to have a kind o' tire clearinghouse thread (if one doesn't exist already... I'm quite lazy, you know) where people can look for winter-specific tire reviews.

Right now, running Bontrager XR3 Team Issue 2.35 both front and back on a Surly Ogre SS. I'm running them tubeless (because why not?) on Stan's Crest rims, 20psi for trail duties and 30psi in town. I've been out on groomed XC ski trails, ungroomed biking and hiking trails, and taken them through deeper (>4") snow in-town. On the groomed trails, they gripped well, presenting little to no difficulty climbing- and bombing-wise. Traction was steady except on fast curves, where the rear end began to slide out ever so slightly. Cornering generally features some Tokyo drifting-style maneuvers. In deeper snow in-town, straight line traction was fairly good. Over packed ruts or through deeper banks, the rear end especially wanted to wander, but generally no complaints. The tires inspired enough confidence that I never really held back on the throttle which, I'll admit, in fairly deep snow on a 29'er SS isn't hard to do. I would recommend these for hardpack snow and snow up to ~2". Beyond that, I wouldn't recommend them for deeper snow, as the lack of cornering traction makes tight maneuvering dicey in loose conditions.

Let's hear what you're running, kids! Remember, it's for science.

lasauge 

For the record, I'm a 150lb rider with plenty of winter experience and a decent bike handler. I ride 700x23 road tires even when there are still a few patches of ice left on the ground without undue worry, so my tolerance for tire slippage is high. Here are some of my tire impressions:

Continental Top Contact Winter, 26x1.9 - these are excellent tires for city riding in winter if you don't have enough ice to need studded tires, they have a lot of grip on pavement that is cold and wet or covered up to 4" of snow, perform acceptably well on roughly packed ice as the tire volume helps dampen the bumps, and they are just narrow enough to cut through slush. Rolling resistance is quite low for tires of this width. The one place these tires do not perform well is over loose dirt or gravel trails covered in snow or ice, the texture that gives them added grip on cold and wet does absolutely nothing on loose soil, you might as well be on thin road slicks. Cannot comment on service life, yet, but my experience so far says that the rubber is fairly resilient and much tougher than conti's road tires, which tend to square off rather quickly.

Michelin Country Rock, 26x1.75 - a fair tire for winter riding, very inexpensive and hard wearing, work acceptably well on packed ice, snow up to 6" deep, and over both pavement and dirt. However, when the pavement is dry these have noticeably high rolling resistance, and in temperatures below zero the sidewalls become very stiff.

Schwalbe Delta Cruiser, 700x35 - These tires perform surprisingly well in winter conditions, particularly over dirt and gravel covered in snow. On pavement these are suitable in a few inches of snow and are acceptable on small patches of ice. These do tend to slide more than other tires on piles of slush or packed snow.

Kenda Small Block 8's, 700x35 - These are great gravel tires and work well if you're going to ride trails on a snowy day as long as the temperatures are low enough that mud isn't much of an issue. On pavement these cope with snow and slush well enough since they're narrow enough to sink through it and the tread provides more traction in such conditions than a slick would. However, traction suffers on icy pavement with these these tires, and they are definitely not suitable for muddy conditions especially if the local dirt is very fine, since mud packs into the tread and you can end up carrying around several pounds of soil on your wheels.

elcruxio

Specialized ground control bliss2 ready 2.1 29er.
Absolute bomb for winter conditions. The tires don't harden up even in extreme cold. Low rolling resistance on snow. Supple casing follows snowy ridges well and keeps grip on even the most technical snow trails.
Doesn't really work as a rear tire. The smallish knobs don't give enough steep uphill traction but as a front tire very good.
requires a bit higher pressures due to very thin casing and sidewalls. Work best as tubeless. These will be my go to tires from now on.
light
If only these were made as 2.5"

Schwalbe Nobby Nic 2.35" 29er
Also good. Have not tried as a front tire but as a rear tire works very well. Gives amazing grip on steep snowy uphills. A bit thick but stays supple in extreme cold. Allows low pressures. Heavy.
Rolling resistance on snow is ok

Schwalbe Hans Dampf 2.35" 29er
This tire SUCKS!
1) the rolling resistance on this tire is amazing. It adds something between 50-100 watts to your rolling resistance. No, I'm no kidding. It's friggin ridiculous. It would be more efficient to ride with a empty tire than with this. I can't even... sigh
2) Absolutely no grip in sub freezing temperatures. This tire will wash out in every corner even in packed snow (where it's should not be physically possible). It locks up when braking in hardpacked snow easier than a slick.
3) the tire hardens to a rock in sub freezing conditions. It looses all suppleness and it doesn't really matter whether you have 1 bar or 3. The tire is similiarly hard regardless of tire pressure.
4) heavy
5) develops cracks in sub freezing conditions. Aka. cracks which go through the tire and leak out all your air. I noticed the cracks after a catastrophic failure in the woods. The tire has ~100 different sized cracks from 1-3cm in length some going through the tire.
6) the extra width doesn't really give extra float due to above
All in all I am very disappointed in this tire. Schwalbe should have warned buyers that this tire should never in any conditions be used in the winter.

cyccommute 

I've not found anything that works as well as the Panaracer Dart/Smoke combination for all season riding. They wear like iron, grip on hard or soft terrain and have handled my winter (and summer) commuting and riding duties since they were introduced in 1992. The Fire Pro's work okay but they just don't quite handle the snow and ice as well.