Prior to entering the scales, go into the office and talk to the person that will check the weight - tell him/her what you want to do. Prevents confusion (what the %(^(^ is that dude doing?).
I'd weigh the vehicle/trailer together and obtain the following weights:
Front wheel - vehicle
Rear wheel - vehicle
Then go off the scales - park the trailer out of the way - re-enter the scales with your tow vehicle and weigh the following:
That should give you a good picture of everything.
Example: The difference in rear wheel weights of the two tests, above, would be the hitch weight of the trailer. Add this to trailer axle weights for gross weight of trailer. Gross weight of trailer plus tow vehilce front/rear axle would be combined vehicle weight.
Hope that makes sense.
Oh, when 18 wheelers enter the scales, they weight front axle, drive axle and trailer axle. They are checking the following:
Front axle not overloaded
Drive axle not overloaded
Trailer axle not overloaded
TOTAL - GROSS - weight 80,000 pounds or under.
Don in E Texas