Abstract: A vehicle suspension system may include a first suspension assembly operably coupling a first wheel to a chassis of a vehicle, a second suspension assembly operably coupling a second wheel to the chassis where the first and second wheels form a pair of front wheels, a third suspension assembly operably coupling a third wheel to the chassis, a fourth suspension assembly operably coupling a fourth wheel to the chassis where the third and fourth wheels forming a first pair of rear wheels, and a payload extension kit that is attachable to the chassis non-permanently. The payload extension kit may include a fifth suspension assembly operably coupling a fifth wheel to a sub-frame extension of the payload extension kit, and a sixth suspension assembly operably coupling a sixth wheel to the sub-frame extension, where the fifth and sixth wheels form a second pair of rear wheels.