Yup. That's the main thing. The factory tires were not very heavy duty and that was a limiting factor to GVRW. Buy a set of Rickson 19. 5" wheels and some 14-ply commercial-duty tires and you have that problem more than licked; except it will still say the same under-rated GVWR inside your door jamb.
Especially if you have the Dana 80 rear, which was extremely down-rated by the factory. Chevy 1-ton K-30 duallies, as well as motorhomes and stepvans etc, used the Dana 70 for a very long time with great success. The GM Corporate 14-bolt 10 1/2" ring gear rearend was actually a little stronger, imo, but it was usually configured as SRW only. The Dana 80, even the so-called Dodge hybrid, is even stronger.
Duallies have their place, but the HD 2500 (Dana 80, heavy springs & manual trans) is so close to being the same truck there is simply no real difference except the 2 extra wheels and the wider stance that duals provide in the rear. That width in turn provides noticeable stability if both trucks are stock, plus you get the extra load bearing ability of the 2 extra tires. The 2500 can be upgraded to nearly match, or even exceed, that stability and tire rating.
But you will always have the DOT to contend with and they don't care if you put 2 1/2 ton Rockwells under that truck, they will still go by the sticker in your door jamb for GVWR. It is a point of pride with them to utterly ignore logic, reason, and responsibility when it comes to generating revenue through fines.
The real weak point in both trucks from a weight-carrying standpoint is the Dodge brakes (and brake lines, right Kenny?).