According to Trailer Life magazine, the manufacturers are signing up to have the SAE (Society of Automotive Engineers) set up equal parameters to test each vehicle and set the GCWR, GVW etc. That will get everyone on the same playing field. Toyota has already signed up and ended up haveing to reduce their tow ratings.
And regarding the current GCWR's, if one pulls more than the truck is rated and piles up on the hiway, due to your fault, my fault, nobody's fault, then the insurance company will forget they know you and you will probably get a visit from the police and/or the attorneys for the other party with a whale of a big lawsuit.
In other words, pull the heavy over rated loads at your own risk.
Sorry DBoyd, but not a single word of that second paragraph is accurate or true. Are you a commissioned internet weight police officer?
Your insurance company has a contract with you that is binding and enforceable. If you have an accident pulling a fifth wheel trailer that is several thosand pounds over GCWR and anyone cares, your insurance company would pay for damages as required and MIGHT possibly cancel your policy or choose to non-renew at the end of the policy term. I have been an insurance adjuster. Insurance companies don't cancel policies before paying except in extreme cases where the insured has deliberately committed fraud or violated specified clauses in the insurance policy. Even in those cases the insurance company normally pays then cancels to avoid lawsuits and bad publicity.
DOT officers don't know or care a whit what the manufacturer's rated towing weight is. What they do care about are gross vehicle weights and gross axle weights. Those are enforceable numbers. If you are caught over GVWR or GAWR you can and probably will be cited for a violation.
You will never find any reference to manufacturer's gross combined weights or manufacturer's towing weights in any federal or state DOT commercial vehicle codes. If GCWRs were considered important and enforceable by DOT codes they would be required to be posted on the door post of our trucks just like GVWR and GAWRs.
Can you offer facts about any lawsuit in any court in America where anyone has been cited for exceeding the gross combined weight rating of their truck?
My previous '01 and '06 Dodge Rams were each licensed by the State of Texas at 26,000 lbs. The GVWR of the '01 was 10,500 and the '06 was 11,500. The GCWR of the '01 was, IIRC, 21,000 lbs. and the '06, again IIRC, was 23,000 lbs. I was completely legal and was inspected by DOT officers in several states several times towing heavy trailers.