The R2 pattern has much deeper lugs than the R1. They are intended for use in rice paddys and other really wet places. Due to the inherent flexibility of the deep lugs, they don't provide as much traction as R1s will in normal soils. There is also an intermediate between the R1 and R2 marketed as the R1W, the W standing for Wet soil. If you go this route, check the rolling radius/diameter/circumference to make sure it will clear your fenders and not screw up the lead ratio between front and rear axles in 4wd.