Good points, Nay, about the carbide, and Cj80cruiser, about the limited sizes. In my case, I want to stay with the standard 31" diameter because of towing issues with steering geometry, but I want the agressive tread for occasional mud trail riding. With the MTZ's, and no buddy truck, I trend to backtrack a lot. The Geolander tread design is very close to the Icelander, but if you look closesly, every other edge lug on the Geolander is cut off by half but is completely cut off in the Icelander. This brings up another negative on the Icelanders regarding spares -- the tread pattern is directional. I'm figuring to just keep my MTZ as a spare, since it is the same size. My interest in the carbide is on slippery boat ramps, but siping might work as well, or even better. I don't have the experience and hope to learn from this world-wide forum.