Ford/NH 1620 turf tires and switching to R4's

[dougmccabe]

I have seen many people saying I need to get new wheels to go from 13.6-16 Turf tires to R4's. Another site I saw someone said the 12.4-16 R4's are equivalent in size and lead/lag for the 4x4 is the correct ratio of 1.4%. has anyone done this? Any issues?