I feel like I'm a broken record but manufacturer rating are nearly bogus.
In order to know how much weight you can tow, you need to know the GVWR, GCWR, axle ratings, tire ratings and actual weight of the tow vehicle when it is loaded up and ready for a trip.
I'll use my truck as an example.
2002 Ford F-350 crew cab, 4x4, long bed, diesel.
GCWR - 20,000 lbs
GVWR - 9,900 lbs
RAWR - 6,084 lbs
Vehicle weight - 8,400 lbs
I have 1,500 lbs of capacity left in the truck itself and 11,600 lbs of towing capacity before I go over my GCWR.
My 29ft trailer has a GVWR of 7,400 lbs and I am very close to that when we go camping. I also get a tongue weight of about 800 lbs when I'm hooked up.