The data plate on a M35A2 says 10,000 pounds on road. If you run heavier and get into an accident, you may well find that your insurance company won't know you, since you clearly violated the manufacturers specs. I think the reason for the relatively low tow weight is two-fold. One, the pintle hook is only held on with one nut, as opposed to big rigs that have a beefy 4 bolt hookup. Two, the pintle hook is located very far behind the wheels, as opposed to a dump truck, let's say. If you dynamite the brakes, your towed load will lurch forward and downward onto your pintle hook, thereby raising your front wheels off the ground, potentially. Not a good thing. On a dump truck, the pintle is hugged up tight against the rear pumpkin, so downward force on it creates far less lifting force on the front of the truck. Irv