If you can put a band of sheet metal or tin foil around it you can cut it with a plasma cutter.
It'll be messy and stinky, but no worse than a skinny wheel and probably a lot quicker.
I once had to cut stall matts,
Discovered liquid soap to be a good lubricant.
Folding over a 2 x 4 was a good help.
On a tire ,soap might be your best bet.
I cut pickup tires off a rim with a Sawzall, but that's a lot smaller than a tractor tire. Once the bead is cut I would be tempted to try a chainsaw. Use caution if you try that though, the chain tends to bounce off more than when you are cutting a tree down.
And don't ask me how I know that...
Once you get a hole started, they cut just fine... until you hit steel.