Probably a cost of manufacture thing. If you use a standardized frame and brake mountings across the board, that keeps costs lower. The LT just looks like it uses a different wheel.
One thing, my 3.2 could not keep higher pressure tires on the rims, since the plastic wheels did not have a seating bead on the rim. After a while, I took to using contact cement on the bead to help hold them on. Does the LT have a metal rim, or is the entire wheel the fiberglass composite?