[JRTJH]

My "best guess" is that the distance from the pin to the center of the axles is probably 2 times the distance from the rear bumper to the center of the axles. If that's close, then a 1" drop on the pin will be a 1/2" rise on the bumper. There's not a lot of change in bumper height by adjusting the pinbox a couple of inches one way or the other (up or down)…. For most trailers that I've seen, it's around 2:1, or twice as much pinbox movement as bumper movement.