Tried to install the 2-link chains on the rear of my BX-2670 today. 26x12-12 R4's I guess is what you call them. Tire chain size, 26/27x12-12. The chains don't seem to be any too wide, but probably sufficient. Length, however, is a different matter. I've removed 2 cross chains already, and they are still loosy goosy. That was as far as my back and hip would allow, I'll have to tackle them again another day.
I do have some 26x12-12 turf tires on Wheel Horse wheels, and I'm beginning to hope the wheels will interchange. Chains work best on turf tires anyway, and a quick zip zip with the impact will change wheel/tires in a lot less time and work than putting the chains on every fall anyway. In fact, that's what I've done the last 20 years, just swapped summer tires/wheels for winter chains/tires/wheels.