THe information you seek is cryptically hidden on the Dodge Ram website. Took me days to find it for my 3500 Longhorn. The other thing is, if your looking for a model that is outside the current build year it is even harder to find. If you do find the Towing Capacity sheet for your truck, ensure that you save a copy somewhere on your computer and smartphone. It looks like someone has already posted a link to the area in previous posts.
As for how the "cops" know, it is pretty easy to tell if you are over limit, the rear end sags, rear springs are compressed and the tires look like aircraft tires, bulging and compressed. They've also seen so many of these overweight units that they can spot them a mile off.
I am currently trying to find a 5th wheel unit that sits inside the weight restriction for my 3500 Longhorn, you'd be surprised just how light a unit has to be to stay inside the limits.
A 10,000lb unit that I'm looking at is actually too heavy for my truck based on GVWR and payload limits, but still falls within limits of my GCVR and rear tire ratings. Meaning, I'd be legal inside Alberta Canada, but illegal going into British Columbia. Towing a complicated world.
See my thread http://www.ramforumz.com/showthread....005#post800005
Sorry I can't be of more help, but I'm still learning the ins and outs of towing myself.