There should be a sticker on the door or door jamb that has all of the relevant information. It's more than just the advertised trailering capability. You have to figure in what your axle weights are and your payload inside the vehicle, then you can calculate what is safe to tow.
If you peruse some camper sites, you'll soon read that people recommend going to a truck stop and getting your vehicle weighed 3 times:
#1 - vehicle with occupants and payload. This will give you the 2 axle weights.
#2 - vehicle with occupants, payload and loaded trailer with weight distributing hitch engaged. This will give you the vehicle axle weights as well as the trailer weight.
#3 - same as #2 except with the weight distribution bars removed. This will give you the tongue weight (IIRC).
So, with all of that said, look at the weight stickers first to find out what your capacity is, then look at the manual to see what your max tongue weights are. Mine has a 500lb/1000lb capacity. The first number is the normal tongue weight, the second is the tongue with with weight distribution.
Here's a picture of my weight calculation I did once I weighed my rig. I'm towing a 25' Keystone Passport 238ML Ultralight with my '99 Yukon 4wd.