Originally Posted by garyb1st
Recently I've seen several towing guides which state the max towing capacity of the 2005 Ford F250 is 12,000 lbs. The brochure for the same 2005 F250 states the max towing capacity is 15,400.
You're probably comparing apples to oranges.
For 2005 F-250 diesel CrewCab 4x4, the tow rating is 12,500 for conventional towing (i.e., travel trailer). But the tow rating is 15,400 for fifth-wheel towing.
The difference in tow ratings is caused by the weight limit of the receiver hitch that's standard on the 2005 F-250. That receiver is rated for a max gross trailer weight (GTW) of 12,500 pounds with a weight-distributing (WD) hitch. But for a fifth wheel trailer with a 5er hitch rated for 16k or more, hitch weight limits do not restrict the max weight of the trailer, so the tow rating is GCWR minus the shipping weight of the truck minus a 150 pound driver.
If you replace the stock receiver with a Reese Titan that has more than 15,400 GTW rating and more than about 2,000 TW rating, then your tow rating for a TT goes up to the same as the 5er tow rating.
But the 5er tow rating is not a good method to determine the max trailer weight of a 5er you can tow without being overloaded. The 5er tow rating is simply the GCWR minus the shipping weight of the truck with skinny driver, and ignores hitch weight. 23,000 GCWR minus 15,400 tow rating = 7,600 pound maximum wet and loaded truck weight. So if your 2005 F-250 diesel is a CrewCab 4x4, you can tow some 5er trailers that weigh 13,400 pounds without exceeding the GCWR of the truck only if your F-250 diesel weighs less than 7,600 pounds when wet and loaded for the road, including 5er hitch installed and a full tank of diesel, but without the trailer tied on. 13,400 tow rating plus 7,600 wet and loaded truck weight = 23,000 GCWR of the tow vehicle.
With a wet and loaded truck weight of 7,600, the max hitch weight is 2,400 pounds before you exceed the 10,000 pounds GVWR of the F-250. That's 15.58% of the 15,400 max trailer weight. That's nice for Ford advertising of tow rating, but most 5ers that gross 15,400 will have a pin weight of about 18% of gross trailer weight (GTW).
But if your wet and loaded F-250 weighs more than 7,600 pounds, GCWR is no longer your limiter. The GVWR is your limiter, and that limits hitch weight. A 12k 5er with typical 18% hitch weight (pin weight) will have a pin weight of 2,160 pounds. 10,000 GVWR minus 2,160 leaves 7,840 for the max weight of your wet and loaded truck before you tie onto the 12k 5er. Trust me, most 2005 F-250 diesel 4x4 CrewCab trucks with passengers, tools, 5er hitch, full of fuel and maybe some other stuff in the truck will weigh more than 7,840 pounds before you tie onto the trailer. (My '99.5 4x2 weighed almost 8,000, so a 4x4 with my stuff in it would weigh almost 8,400.) So even a 12k 5er will probably overload your F-250 that has a 5er tow rating of 15,400.