They have a great reputation for studded winter tires. I have never tried the studs. I have used the Tenmaster Red rear 120/90-18 and the MaxiGrip red front 80/100-21. I had to use something other than the S-12's due to availablity issues last fall. I can say that these tires are good in soft and medium conditions. The knobs are extra tall. The red stripe have heavy side walls and they are not quite as good as the the S12's in the soft terrain or deep sand. The knobs last pretty well and do not chunk. The front is OK but does not inspire you like the S12 to go in fast into a quick turn. Overall a great set of tires. I did Moab on them and had no issues with slick rock and other difficult trails. I got mine from www.werproducts.net
They are good guys.
However S12's still rule for Michigan!