LS doesn't care one way or the other. The tractors get tires mounted at the assembly centers according to what the dealer orders. If what he has on his lot is R4s, then R1s would be a special order. If he doesn't have it on his lot and has to order it anyway, then there's nothing special about it. I bought my XR3135HC direct from a regional assembly center near me, and spent a fair amount of time talking with the guy who runs it about how the LS distribution works. The engine, frame, and cowl arrive assembled and crated from Korea. Nothing else gets assembled until they get an order form a dealer.
I asked for R4s on mine. I saw one at his place with turf tires, but have never seen one with R1s. Seems most people order them with R4s.