This answers a question I've had as well. My used tractor came with R4s. In order to get enough clearance between chains and stablizer arms on the 3PH in the winter I have to extend the wheels so they are wider than the snowblower. This is a problem because there are drop offs on each side of my driveway.
Wanted to go to R1s so I would have clearance needed while not having the tires so wide.