Tongue weight capacity - technical question.
 

Before I start, I already know how to measure the actual tongue weight of a trailer, but I have a different problem & I'm hoping someone here might be able to make some suggestions.

I'm trying to establish a method to determine the tongue weight capacity for a towing vehicle. While this would normally be a function of rear axle load capacity, this particular vehicle has a high rear weight bias - much like a 911. Because of this I am certain that the front wheels will leave the ground before the rear axle reaches maximum load. The hitch point is already established, so moving it forward is out of the question. So what would be the basis to determine how much vertical load the hitch can take?
I am thinking that a I am going to have to work along the lines of a % reduction in front axle load, but does anyone have any better suggestions?

Actual tongue weight should always be 10% of the actual trailor/load weight. Therefore if you wanted to tow a combined weight of 1500lbs the properly loaded tongue weight should be 150lbs.

So now there are two issues. Can the tow vehicle safely handle the tongue weight as described above on the hitch and can it handle the total tow weight in handling and braking situations?

I have seen Harley guys on a dresser (and yes they make a hitch that bolts on) tow a ski-doo /wave runner and trailor to the beach. I would bet that the trailored load way exceeded what I would consider safe.

I believe the safe rule is total towed weight should not exceed 1/2 of the total tow vehicles weight. Big-@ss pick up trucks are excluded in this example

" Trailer Tongue Weight is the downward pressure that the tongue of a fully loaded trailer exerts on the hitch ball. Tongue weight can be measured on a commercial scale, or on a bathroom scale. Just place the weight of the trailers ball receiver on the scale and multiply by three. Make sure the trailer is level and the wheels are chocked."

Check out http://www.sherline.com/lmbook.htm#refrn23