What tire should I put on my road/commuter bike to prepare for a New York winter? I have a road/commuter bike (Specialized Tricross) I use for commuting daily in New York City.  The roads here can be quite harsh, with everything from leaves and branches to glass and potholes.  The roads here gave me plenty of flats on the stock tires, so I replaced them with 28mm Continental Ultra Gators, and haven't had a flat since.  I already have full coverage fenders with mudflaps on, and they've been very helpful on rainy days.  Now winter is approaching and I'm wondering whether to swap out the tires.

I rode in winter here last year, so I'm familiar with the challenges, but I'm not perfectly satisfied with how my current setup performed.

The issues are:


About 60% of the time it's really no different from the rest of the year, just colder.  A significantly heavier or knobbier tire would slow me down on these days.
About 10% of the time you get flurries or light snow that doesn't stick, and the smooth tread on my tires makes turning a bit dicey, but otherwise manageable.
About 10% of the time there is some fresh snow on the ground, and turning can be very challenging, but going straight is fine.
About 10-15% of the time there is older snow on the ground, mixed with patches of ice.  I am able to proceed in a straight line at a slow and steady pace, about 10-12 MPH, occasionally getting off for steep hills and sharp turns.
5% of the time conditions are such that it is completely unrideable, and I end up walking the bike home if I happen to have ridden it to work in the morning.  I will often avoid riding in the 10-15% conditions mentioned above to avoid being faced with these conditions later in the day.


Do I need a completely new bike for the winter (or should I just take transit 20% of the time), or will putting on different tires help?  Another possibility would be to buy a new front wheel with a very wide tire, and switch out wheels on bad weather days.  Has anybody tried this out?  Would I be OK with a smooth tread on the back?
You say you've got a small apartment that can't accommodate two bikes, but how about two sets of wheels?  The only thing that can deal with ice is studded tires, so for those 20% of the days that include ice, you need studded tires.  Your Tricross should be able to accommodate such wheels, so it would simply be a matter of changing wheels rather than buying a whole new bike or using transit.

As for those days it seems okay in the morning but turns into an icy day in the evening, all I can suggest is paying careful attention to the weather guessers and guessing conservatively.