GVWR

One thing you can do if you can is to weigh going in a place with a scale. Lots of places have scales with either digital displays or someone will give you these weights. You really have no use for "legal" weights so a general weight should work.

 

Two axles with a total of eight tires vs. six tires.
You've never hauled ag in NC, I take it... they get nitpicky as #### about it. I got tagged grossing 32,9 in a single axle, and their conclusion was that I was only legal to gross 31,6 on the Interstate, and 10% more on secondary roads. Same thing here in CO when I was running ag for Pioneer... those 54k trucks could only gross 51 - 52k on the Interstate.
I don't know entirely the ins and outs of it, but it is there.

 

I'm not disputing your word, you might very well be correct. I have never seen wheel base measurements change the GVRW as certified by the maker unless of course another company modified the truck. I would be interested in seeing this in the actual law inter or intra state.

 

I would also be interested in seeing the law that changes the allowed ratings, especially on the interstate only.