Dunno what they get ya at your local DMV, but around here for a single axle the GVW is 1.5 times the scale weight.
If I get that right anyway, I can be pretty dense when the DMV is talkin to me, it's usually painful when I go there,... Either way, in my case, we figgured the truck as 8,100x1.5=12,150.
The extra 4,050 lbs gives me the 2 ton capacity I'm supposed to have, but again, depends on how the rig is set up & all that. I'm kinda thrown by the old GVW sticker on the side of mine says it's rated to 24K tho,...

I'd go by what your state does to figgure it, if for no other reason than keeping the local yokels off your bumper in the event you actualy mean to haul stuff with them. Other option is to see if there are owners manuals in the online libray that will give you the rated GVW for the year it was built.

1956 GMC 370 dump " 'Tater "
1970 VW Volksrod "the Black Bomber"
2007 Chevy Avalanche
2020 Jeep Cherokee Trailhawk,
2005 Harley Davidson FLHTCUI

I dig all cars, old and new, whether they were hammered out of American iron, German steel, or Japanese tin cans. Being unable to appreciate them all is missing out on a world of great things.
But thats just MY opinion! :P