Payload as mentioned (if a 1500) is the biggest limiting factor.
After that the rear gear ratio is the limiting factor for most every series - 1500-2500-3500 SRW.
Be careful going by what RAM says you "can" tow - most of those max numbers are pulling a wagon or something similar.
For ex. I can "tow" 10,500 lbs (or something like that) with my 1500. But if it's a camper or something like that and will put 10-15% of it's weight on the hitch, my real limit is more like 7000-8000 lbs max and that is if I am the only thing in the truck and run a light hitch weight. But if it was a wagon that supports all of the weight and I am only pulling it, then an easy 10,500 .
Most people seriously underestimate how much is in the truck and the true trailer hitch weight - then you blow past payload or rear axle max loads.