Here're a couple of pics of my mobile oven (21") that rolls on and off my trailer. The six wheels on the trolley spread the load as the trailer floor is not that strong. They also allow the trolley to bridge the small gap between the stand and the trailer when loading and unloading. The oven usually stays in the trailer for cooking although I can dismantle the steel stand and roll the oven back onto it for cooking. It really is wheels on wheels.