I personally don't think studded tires are worth it. I use ordinary ol' inverts in the snow and haven't ever had a problem that wouldn't have occurred with studs. You might be able to go a little bit faster on studded tires on the ice, but the weather here in CO is so bipolar that the benefits of studded tires are pretty much outweighed by cost and additional rolling resistance. I might buy them if I lived someplace icy.