2" spacers on the BX. Running R4s. Max size that Kubota recommends. The ground clearance on the BX is minimal. IIRC, just over 6". Relative to width you would think it would feel relatively stable. Bx rides rough and bumpy relative to the NH. Gives the feeling of less stability even though I'm sitting much closer to the ground than on the old NH. Guessing the much heavier, wider, larger wheels of the NH gave it more stability.
Didn't realize how little clearance the tires have on the inward side until looking at one without spacers at the dealer a couple weeks ago. Chain clearance would be minimal without. Spacers were +$200, but the additional clearance and hopefully stabler ride made it worth the $$$s.