I agree with what Mike said about CG shift.
My hitch is located ctr on rear axle and have little sag, truck above level in rear.
Also the True pin wt calc is also accurate but even if the True pin wt ends up being less than calculated using the total truck wt diff, you still have the actual load applied to the trucks rear axle whether that is actual pin wt or some of the front wt transfered back.
We need to take that into account when loading rear axles and tires.
So in theory, the total truck wt method is valid for actual True pin wt, but for application purposes, we should use the rear axle calculation method for applied wt to the axle.
Stacey, that must be why you do the calculations on your weigh sheets the way you do??
Does that make sense? Now I'm just wakening up!!
Cheers,
Bill