Originally posted by elgoatropo
That's why I used the osmosis metaphor. The weight does not get to the rear wheels through proximity. The ballast acts along the longitudinal axis, changing the net distribution of weight. To get the most change for the least added weight, move it aft. Put it on an outrigger if you want.
I'm not sure I picked up on the osmosis metaphor...
The longitudinal axis is exactly what I was talking about. The truck with weight in the bed becomes a simple machine called the lever.
If you place weight behind the fulcrum (the rear wheels in this case) you are causing an upward force at every point forward of that fulcrum.
If the outrigger was far enough behind the fulcrum it could lift the front end right off the ground.
If a weight of 600 lbs was placed at the most rearward part of the bed which, for sake of example, is 3 feet behind the rear axle and the truck is a total of 15 feet long that means that the front end of the truck would be 150 lbs lighter in the front. It seems to me to be a signifigant reduction of weight on the front wheels. If the 600 lbs was placed right over the rear wheels the weight would be right at the fulcrum and would not reduce the weight on the front axle and place all the added weight on the rear. (To me the most effective spot for the ballast)
I used the 600 lb figure cuz that's what I put in my truck bed during winter.
Right OVER the rear wheels.