I try to stay within the tire ratings of my truck. Of next importace would be axle rating. I see little point in a gvwr and pay no attention to my truck's gcvwr. At times my truck is used to haul a 32000 lb gooseneck trailer which it handles fairly well on the prairies - The exhaust brake might be too weak to safely pull that kind of weight on the mountian freeways. Some hills off the interstate might make the truck inadequate to handle the 15500 lb trailer it is rated for. To a large extent I view it as the truck needs to be able to handle the weight put on it and the trailer needs to handle its load - and these numbers will vary depending on the roads you intend to travel.