Weight distribution/anti sway - Event Date: 23 Jul 2017

I would recommend the 600 pound spring bar set up. Going more than that the bars are to rigid, and will actually begin to cause damage. You always want to be as close to the actual tongue weight as possible. I've been told this is not a "bigger is better" situation. Otherwise I'm pretty sure they would only sell the 1000 pound set up. 

There is no reason to expect damage from stiffer wdh bars. Regardless of what bars you have you will be setting up the wdh to bring the weight on the front axle back to where it was before the trailer was attached. On my Highlander with the 179 at 500 lbs tongue weight that was a tension of about 750 lbs. You would have the same tension on a lighter wdh to achieve the same result. That's just the way the math works out.

So the problem with too low a rating is that the bars might fail in bending when hitting a swale if they don't have enough reserve capacity beyond what is needed to load the front axle. The problem with heavier bars is that the ride might get stiffer than you prefer. I ran 1000 lb bars on my rig and the ride was fine.

Isn't that a uni-body SUV?  If it is, you may not be able to buy a hitch that can accommodate a weight distributing hitch.  With your self-adjusting air suspension, you likely don't need it, either.  I use and recommend a friction sway damper as suspenders.  But, if you get your tongue weight %-age right, you won't need that either. 

An air suspension is not at all the equivalent of a wdh.

All an adjustable suspension does is bring the ride height of the tow vehicle rear axle up. It does nothing to place weight back on the front axle, which goes down, not up, when you attach a trailer.

Having sufficient weight on the front axle is critical to safety and h
proper handling since the front axle does the steering and had the best brakes. So by all means get a wdh if you have a relatively light yuw vehicle for the trailer youre hauling around.

Of course, regardless of whether you have a unibody or body on frame vehicle, do not exceed
your tow vehicle, trailer, and combined vehicle specs, and don't use a wdh if the vehicle manufacturer disallows it.

In Europe and elsewhere there are different standards for rating tow capacity. So theoretically identical vehicles can have different ratings in different jurisdictions.

This is very common in all kinds of products. As an engineer responsible for global product certifications I saw this all the time.

There are many reasons for this, some purely a matter of how the standards evolved, some based on real differences in usage. We for example travel longer distances at higher speeds, have higher mountains, and have more extreme weather than in most other countries. In many countries there is also specific training required for towing.

Regardless, we and the product manufacturers that sell here have to abide by our standards, so what a similar vehicle is rated for or what the theoretically identical vehicle is rated for elsewhere is not material. It is illegal to overload your tow vehicle, and that includes not only trailer and tongue weight but also gross combined vehicle weight and axle weights. If you get stopped or are involved in a crash and are found to be exceeding your 3500 lb tow rating you will be the one cited. Don't do it.