Flamingtaco

I think the trailer weight without WDH (5000lb) exists because of yahoos that have no clue what their tongue weight is and don't intend to check... A WDH ONLY applies torque to the chassis to shift weight onto the front axle, it does nothing to strengthen the receiver and make it more capable of pulling or stopping weight. As the pull/stop performance of the receiver does not change with a WDH, the only number that actually applies is the max receiver or max vehicle tow capacity.

Realistically, if you are exceeding 5000lb, outside of boats, you should be over 500lb tongue weight. In posting a 5000Lb limit, they are getting a lot more people to use WDH's when they are needed that would otherwise just guess that their tongue weight isn't over 500Lbs and move on with their day.

smokeywren

A properly-designed WDH shifts tongue weight (TW) off the rear axle and distributes it both forward to the front axle, and rearward to the trailer axles. Ideal weight distribution is 20% to 25% of TW distributed to the front axle, another 20% to 25% of TW distributed to the trailer axles, leaving 50% to 60% of TW on the rear axle.

The TW rating of the receiver is usually the limiter of TTs that have average TW of 13% of gross trailer weight. A WD hitch rated 5,000 gross trailer weight and 500 TW will exceed 500 TW with a trailer weight of only 3,850 pounds.

Right. Because TTs, enclosed cargo trailers, and utility trailers average 13% TW. 500 pounds TW is a TT that weighs not more than 3,850 pounds. A 5,000 pound TT would have TW of 650 pounds, thus overloading the hitch.

Turbo_Bimmer

Interesting discussion.
Ford says that by adding a WDH, the towing capacity is increased.
The reason I suspect is that the rear suspension is soft on a F150, and it will drop without a WDH and with a lever effect on the rear axle, will make the front axle too light and dangerous.

Adding air bags (no more sag), will not increase the towing capacity of the F150, because the leverage effect is still there, just acting higher.

That's what I don't understand... or believe.

In the F250 SD towing specs for 2019, the towing capacity for most configurations is the same for 'Max Wt Carrying' than 'Max Wt Distributing.
The only reason I see is that the SD has stiff rear springs, so no sag. So why does a F150 with add-a-leaf or air bags can't tow the maximum capacity without a WDH?

Maybe it could, but Ford doesn't want to be responsible if someone doesn't install the parts correctly?

5.0GN tow

The SD trucks are now rated to tow full capacity with NO WDH because of the new hitch they have, and the suspension. The newer 17 and up SD hitch extends way up the frame and on 350s at least, (not sure about 250s) is a 3inch receiver, not a 2 inch like the 150s. Those limits don't apply if using a reducer to use a 2 inch ball mount as the ball mount would probabaly not be rated to handle the tongue weight.

My 16 SD has a 2.5 inch receiver which also has a greater 8500/850 non WDH rating and 19000/1900 WDH rating. If I use the reducer to drop it it 2inch the rating drops to 12500/1250. Which is pretty close to as high as a hollow shank 2 inch ball mount goes. I have pulled a very heavy dump trailer with the truck with no WDH as their was no way to hook it up to the type of trailer frame. The hitch weight was pretty minimal as all the weight was sitting on the axles. It towed great and weighed around (listed 4k dry weight) 12k as I had 4 tons of gravel at a time in it. It was an easy pull with SD.

Flamingtaco

The prevailing factors are vehicle weight and wheel position. A more firm rear suspension improves rear end stability, but generates more front end float and does not significantly change non-WDH limits. Significant (but not major) improvements can be achieved with an active suspension, but I wouldn't want to have to 'float' that cost with the current pricing of these trucks.

Turbo_Bimmer

I would have thought a SD, even if it is the earlier generation, would have a higher non WDH rating.
The new 2019 have 15000 without a WDH with 4.30 gears. Is it only because of the aluminum body? It's a big difference.

acdii

Adding bags, or other devices that raise the rear under a load does nothing to transfer weight forward to the front axle. The rear axle is a pivot point when a trailer is dropped on the ball regardless of where the body is in height. The front will still be light until a WDH is used to transfer the weight. Stiffer springs just make for a harsh ride when unloaded and a great majority of 1/2 tons are empty most of the time.

5.0GN tow

No it's nothing to do with the aluminum body, it's how the hitch is designed. The 2017 and up the hitch extends further forward up the frame and distributes the weight over more of the truck. They designed it to avoid having to use a WDH. In defense of the older set up, most SD towing is usually GN or 5th when it gets up much over 10K.

8100hd