Try loading a loaded 13.6/12/28" Ford 600 rear tire into your pickup bed ALONE,and get back to me,and tell me how YOUR back feels after that!..
I never thought I could even do it with help,but I had none,and had to roll that 600 lb monster up the ramps alone!..now any "garden tractor" feels like a feather compared to that!..
I always had a crane on my flatbed truck body,I hauled a lot of stuff home with that thing no one else could lift--also used it to JUNK many things I never should have dragged home with it too though!..I really miss having that thing,I had to let a few nice "freebie" tractors go by because there was no way I could load them manually with my back the way it is now!..
I used anti-freeze in my tires, local junkyards were giving "recycled" anti-freeze away free for a few years,so many guys with tractors and backhoe/loaders used that instead of calcuim..I hate calcium,all it does is ruin rims and kill anything you spill it near!..I have a 10' "dead zone" in my back woods where my Ford 600's tire got puntured 15 years ago--nothing has ever grown back except weeds!..a 15' high pine tree died within a week of being poisoned,it dried up and was like balsa wood,and broke off when I leaned against it like it had been dead 10 years!..
Rusty Old Junk,your aware some tractors with lug style hubs like cars in the rear. are often the same 5 lug,4.5" bolt circle as older Ford and Chrysler rims,and many newer FWD cars ,arent you?..some use only 3 lugs out of the 5,but car rims still fit and work great..others with 4 lugs are a 4" bolt pattern ,same as 8" or 12" boat trailer rims use,or old Vega/Monza and Chevettes used (they were 13" though)...so you should be able to get rims cheap at a junkyard..
I've cut the original centers out of calcuim rotted rims,and welded them into some car rims the same diameter before..the fact most tractors wont go over 7 mph means it isn't real critical if you get things a bit off
"dead center"!..I've made "dualie" rears by welding two space saver spare rims together before too..
Robert