I figured out there is one thing I can do after all, but I don't know if it would be worth the bother. Move the spare tire from the back bumper to the front.
Using the leverage weight calculator for a snow plow from my Chev truck manual, and assuming the spare weighs 75 lbs (it is very heavy--I had to take one off to get a leak fixed--was the valve core--had a struggle lifting it up into the truck's box ) I get:
75 x (140 + 176)/176 = 135 lbs on the rear axle from that 75 lb spare.
140" is the distance of the spare back from the axle and 176" is the wheel base.
I am over RGAWR by 182 lbs according to the scales. What I don't know is the exact weight of that spare and whether this amount over RGAWR is trivial or is serious enough to warrant moving the spare to the front.
