And now I am more confused as to what the arbitrary thought is.
A Ram 2500 and 3500 are very different components in the suspension...the dually obviously being more. A 3500 to 4500 is even more different component wise.
And yes all the trucks have similar GVWR, because they share components...2500 to 2500. 3500 to 3500. And then each individual truck has a completely different payload capacity due to cabs, beds, options etc.
Yes. There is capacity left in the truck. But. That 10000 GVWR isn't arbitrary. For the truck to perform safely under various driving scenarios this is what is decided.
I can get a Dakota to pull what my 2500 does...but it sure isnt safe and definitely would not be legal.
And a person who has a truck and lives near sea level in the flat...they could easily overload the truck...but someone who lives at altitude towing up and down grades, will probably have to be close to capacity, or even under.
As with everything YMMV, and only you can decide what is safe and comfortable for your decision.
Good times for payload and capacity...some semi trucks a decade or so ago couldn't do what these RAM trucks are doing today.
Just to clarify, I was talking about DOT/ Registration versus what the truck is built to do (or can do potentially). You can actually take a 2500 to a DOT inspection and get the payload increased, you just fall into a higher registration class, so its definitely not about safety if you are staying within the RAWR and FAWR. its about the compliance with the class. But manufactures do not build these trucks trying to build only to that number (10k), that would actually be costly to do because the fames, axles, suspension, brakes, tires and wheels would have to be different from their counter part (3500 SRW), which they are not (With the exception of the suspension of a Ram 2500 with the coil springs versus leaf springs, but that rating is shown on the RAWR and FAWR).
The example I used was F250 to F350 (as an easier example), as they are actually the same axle (Depending on package, Sterling versus Dana), brakes, tires, wheels and sometimes (Depending if you get the camper package) springs. But their payload is set to 10k versus 12300 (350), I believe the camper package adds a leaf spring to the 250 in which makes it exactly the same exact truck as a F350 (GVWR becomes the same). Not to confuse it further, but if you go the manufactures website of the axles for Sterling and Dana. Their rating is actually close to 10k per axle (20k), way beyond what the RAWR and FAWR (6k and 6040). in which proves that rating is not Based on the axle itself but ALL of the components. The Sterling and Dana are very close in weight rating from each other, I think maybe a 500-1000 pound difference.
To answers your question about 3500 to 4500. I believe Ford uses the same frame across all those platforms (Not sure about Ram), the difference is in the bed configuration, axles. I think possibly the 450 has bigger brakes than its counterparts but I could be wrong about that. But I wouldn't let people believe that 10k number on a 2500 is the safe limit, its not. The safe limit is their RAWR and FAWR, that combined on a 2019 Big Horn Megacab 4X4 (For example) is 12040. That weight rating takes into account the brakes, axles, suspension, tires and wheels. This has been a big subject of debate and many have clarified this about what the 10k rating is actually meant for.