How much weight is safe to put on the Isata 3 hitch?

[bclemens]

This question was posed to me offline, but I am posting here in case anyone else has the same question. I think there is a pretty long thread on this already, but mainly over flat tow vehicles and not dead weight so to speak. So I will post here my thoughts, and try to keep it as simple as possible (which is impossible).

Let's start out by saying that "you the customer" are responsible for making sure you are within your rated weight specifications. While I can answer one question...there are so many other variables that come into play, without knowing those other variables you could still be over weight. It seems like a simple question, but it isn't, so....

1. The GVWR of the Isata 3 is 11,030 lbs.
2. THE GCWR is 15,250 lbs.
3. 4,220 lbs is what you can flat tow (GCWR mins GVWR, that is assuming that you max out the GVWR with cargo and people. This is what you have left over).

The hitch is rated at 5,000 lbs (500 lbs tongue weight). Obviously, if you max out the GVWR, you can't tow 5,000 lbs since you only have 4,220 to spare (but that is the hitch we buy). Most hitches also have a "tongue rating". This is if you are towing a trailer. That trailer might only weight 3,000 lbs, BUT....typically 10% of that weight rests on the tongue which in turn rests on the hitch (thus the two ratings). That means you have 300 lbs on the tongue. This goes against the GVWR just like cargo...so even though you are UNDER the tow rating and UNDER the tongue weight of 500lbs, that 300 lbs MIGHT put you over the GVWR of the vehicle. OR, if if that is not over the GVWR....that adds to the rear axle weight, so you could be OVER the rear GAWR (Gross Axle Weight Rating).

This question was specifically about a rear mounted scooter and if you have enough capacity to get a larger one.

So, now that this has rolled into "not simple" territory, this is what I would do to see if I can load something heavier on the back. (as this question was specifically, can I put a larger scooter on the back)

1. Weigh your current set up on a certified scale how you would normally load it.
2. Get a front and rear axle weight, which should give you a total weight.
3. Subtract the rear axle weight, from the rear axle weight rating...what is left?
4. Subtract the total vehicle weight from the GVWR. What do you have left?

THIS (smallest of the two numbers) will tell you how much heavier the scooter can get. Even then, I personally, would not exceed half the tongue weight with dead weight....so 250 lbs max dead weight, in my mind. Dead weight is cantilevered out...the further away from the hitch, the more the force. Every pot hole you hit is bouncing that dead weight up and down. A trailer will limit this force as it is sort of a counter-balance. A hitch mounted carrier has no such luxury.