The AT-101s will fit your 8" rims no problem and I wouldn't even worry about spares when all the tires on your machine are now. A worst case scenario with a flat in the wood would consist of swapping a flat corner tire with a middle tire until your back to your trailer. Get the new tires and list your 8 used ones on Kijiji as decent rollers if thats what they are. The AT-101s have a decent bar lug with good traction caracteristics in the mud and sand, they really are a good tire.