I know that is what they say to pull "max" weight but one time me and some buddies went camping and I was in my jeep and my buddy was driving his 86 suburban loaded with camping supplies and a crap ton of firewood. Well he broke down going over the pass at unicoi gap near helen. I hooked him up to my jeep (also loaded with gear and another person) and I towed him from the turn to brasstown bald to the pull off at the appalachian trail crossing on the crest of unicoi gap which is all uphill and very steep. I figure the weight I pulled was close to 5500lbs and the jeep never complained. If that is not a testament to the 4.0 I don't know what is. I also need to add that it was also when I had my D35 rear (super 35 kit installed) so yeah, crazy.