DEADMAN: If you purchased the tractor new or used from a dealer, that would be your best option to get R-1's. Someone recently on this site had the same problem with his JD, and do a search here for his solution? I think he traded back with his dealer, and the dealer traded with another customer, that had purchased a JD with R-1's, but wanted R-4's? You will need new wheels for the R-1's, I think, and if your tractor is 4WD, also a set for the front, to keep the gear ratios correct from front to rear?? There is also tractor "salvage yards" that may have the correct size wheels, if all else fails?