The difference in performance is severalfold. Wheelbase, wheel volume relative to mass, overall density, smooth undercarriage. So the wheels on the sherp are able to act as paddle wheels because the buoyancy of the vehicle is so high that the water level doesn't reach above the center of the wheel. The sherp was basically an amphibious vehicle competing with ATVs. For most of these trucks it was an exercise pushing these builds to the limits of their abilities and even beyod. Installing the tires with the tread pattern reversed is advantageous because it creates resistance on the water surface and causes the car to surface and move forward.