I've always made up my own chains, either from old sets I've picked up at auctions or buying components at stores that sell to the logging industry.
Measure your tires and compare them with a set of light truck tires. You may get lucky...If not, buy the next larger set and cut them down.
I had to build one set with one side chain longer than the other to give clearance to the steering ball joint on a 4x4 I had. My JD4300 would have the same problem if I put chains on the front of it....