I have used R1s R3s and R4s and have learned a lot from them. My Yanmar has R1 tires, no they are not rice paddy tires, it is a domestic model tractor. They are great in the mud, working in the dirt, and on gravel. But whe nit comes to the wet Oreon snow, they are awful. R4s are great for load capacity and hold up the best, I have got R3s to go almost flat when doing loader work, the R4s are much more for loader work over anything, that is why contractors and landscapers prefer them. They wer very well on pavement. I have got stuck with all three different tire, the R1s were probably the worst since they dug in really deep very fast. R3 tires loose their grip first for traction, they only have the small gaps between tread so they will pack with dirt and when you run tem on pavement you get a big mess. R1s and R4s are self cleaning for the most part and much cleaner on pavement. In your case sine only R3s and R4s are available I would opt for R4 tires, you get the best of both worlds. They must be good, Deere doesnt even offer R1s for their 2x20 or 1 series tractors.