I think "klenger" hit the nail on the head. The manufactures tow & weight rating guide is just that, a guide. This is mostly for the factory's benifit more so than the customer. They seem to change, based on the competition, more than any design change. You can haul a lot bigger loads than the ratings if you stay reasonable and follow the DOT laws on license and insurance requirements. What I mean by reasonable, is what the general motoring and law enforcment thinks is reasonable. If you haul a house on your big ole gooseneck trailer and go down the highway , "you might be a redneck", but if you haul a 16,000 lbs backhoe on that same trailer or pull a three axle car hauler with three medium sized pickups on it, you will be ok. But all three loads will exceed the tow rating of your truck. I run general hot shot type freight for years with no trouble, but when I got over 26. 000 lbs I didn't make any money at it.
"IF IT AIN'T CUMMINS POWERED, IT AIN'T A TRUCK"
"NICK"