Don,
It does make sense to use the total wt change when loaded to determine pin wt, but in most cases the front axle wt is less when the trailer is on the truck. Mine is acutally 100lbs lighter on the front when hooked up.
Now, that should mean that 100lbs is transfered to the rear when loaded, so then is my pin wt actually 100lbs less than what I think?? The difference between my rear axle loaded and unloaded is 3450lbs but since the front is 100lbs less then it should be 3350?
When Stacey wieghed our rig the sheet shows the pin wt to be the diff between the rear truck axle wt loaded and unloaded, not the diff between the total truck wts.
I maybe shouldn't try to do this after a night shift!!
Cheers,
Bill