Jake is correct in point out that the GCWR is what is important for towing. It indicates how much weight your truck's engine, drivetrain, and frame can safely handle. The GVWR is simply a number calculated from the condition of the truck when it left the factory. The true capacity can be increased or decreased with modifications to the truck. Want to decrease it, well then put on larger tires or lift the truck or lower it. Want to increase the load capacity then add overload springs and higher capacity tires. With some older trucks the addition of an axle truss was commonplace. The truck manufacturers are not testing their trucks, nor the car magazines, based on real world conditions. The only exceptions were the recent 1-ton tests by mrtrailer.com and Car and Driver where actual trailer loads were use during the tests for acceleration, stopping distance, fuel economy, handling. I would not tow a 10,000 lb. trailer with a 1/2 ton truck or a 3/4 ton SUV as they are not up to the task regardless of the manufacturer's specs. If you have a problem with the trailer's brakes how many miles will it take to bring the rig to a complete stop?