Throughout the trailer, hitch, and tow vehicle industry a recommendation of 10% tongue weight for a tow-behind trailer and 15% for a 5th wheel trailer seem universal. They have even been changed to 10%-15% and 15%-25% recently.
Where did they come from? How were they determined? Was it to keep the trailer on the ball in all conditions? If so, a weight-distribution hitch dramatically increases the forces on the ball but there is no recommendation for lower tongue weights with a weight distributing hitch.
With all the GVWR, GAWR, and GCWR numbers are thrown about, the only one with a standard seems to be GCWR with the relatively recent (last 10 years) SAE J2807 standard. And that standard has been widely criticized as not accounting for basic factors such as steering ratio and wheelbase when specs talk about steering wheel angle.
So, where did the 10% recommendation come from?