If you need studded MTB tires. I say get any of the Nokian models. I believe all the models now have carbide studs. You just need to decide what model will suit your type of riding. Me? I ride the Nokian Freddies Revenge that are 26x2.3 wide with 336 studs mounted to a wheelset of Ditch Witch rims which fattens them up a bit. This model might be too larger for your application. But they work for me. These just squeeze into the chain stay of my winter 2002 Specialized Rockhopper...
If you have the money to purchase a set of the cheaper tires... SAVE, your money and wait a couple of pay checks and get the Nokians. You will be much happier. I have ridden the cheaper studded tires, and they SUCK!!! They work okay, but you will be much better off and SAFER getting the Nokians. The grip on ice is CRAZY!!! Much safer than walking on the same surface...
I hear Schwalbe Studded Tires are better now. They have the carbide studs too. But I've never tried them...
Hopes this little bit of information helps.

Nokian Freddies Revenge that are 26x2.3 wide with 336 studs.