You don't need a tractor tire. They can be a bitch to acquire, transport, store, move or get rid of. Find a regular old tire on a rim. After making sure it's deflated, use a hole saw to cut a whole in it. Fill it with sand, glue the plug back in. I used two long axle straps and chain for the harness. The axle straps crisscrossed my chest, you'll figure out the chain. ....or just some thick rope would probably work. Better for pulling as well.
Mine was a regular old 14'' tire and rim. It was quite heavy full of sand, and I'm 240lbs. Go for a smaller tire, or don't completely fill with sand if you are less hefty.