Let me guess....patented/proprietary rims on those tires?

yes, and the tires are custom molded to fit the pattern of the rim. as I've read it, can't fit a regular tire of the same size on the rims because of those segments. also, they're allegedly "mud + snow" tires, per the "M+S" label on them.

Someone here said if you want to replace the tires you have to replace the wheels.