Actually if the original combine rims are 15 inch, and not 16 inch rims, Plus 6 bolt hubs, you want those rims. They are basically what the 60xx used for the 29 x12.50x 15 tires..
The combine weights were mounted on special 15" rims. Those rims are the only 15" rim that they will fit. The inners, two-piece, were mounted on the normal side of the 15" rim. The outer weight is deep, so the rim is already built with the offset for that. My initial assessment is, they will bolt right up. But, the rear track is going to be very wide compared to stock.