Some conditions you'll be fine with a larger (2.3 or bigger) volume tire running lower air pressure, and some conditions dictate studded tires. I run studds all winter and can ride in almost any condition with them.

You haven't ridden until you rip hot laps around a frozen pond using studded tires........can't slide out even if you wanted to. My little guy loves when I pull him on sled around the pond too.