I can't find them on the Specialized site at all, but several years ago I put Armadillo All-Condition tires on my mountain bike, and I really like them. They're knobby enough for traction in a pinch, but they are pretty well smooth on the center when you're riding on the road. I have ~1,000 on mine and they're still like new, and they're pretty puncture-resistant (never had a flat, but don't often have puncturing obstacles around when I ride)...

They look like this: