Don't over complicate this.
2500s have low specified gvws due to the vehicle classification they are in. Which is basically for registration and taxation purposes.
The OPs 2013 Ram 2500 is identical to a 3500 save for an additional rear leaf spring, class 2 gvw limit and the badges on the doors.
Furthermore, save for more springs and 2 more tires, it's the same as a 3500dually.
Don't start getting concerned until your payload is around 4000lbs, although you may need to shore up the rear suspension . Then it's time to look at the tire and wheel ratings once you've got 7500-8000lbs on the rear axle.
