This is interesting, but aren’t the hitches themselves quite different in how they attach to the body? Which would result in different ratings as well? The Westfalia style hitch replaces the rear sub bumper, while the Curt just bolts in externally?
I apologize for not having citations. I was looking at Westfalia vs EcoHitch for my JSW in North America a few months ago. When I realized most of the hitches in Europe and North America had the same ratings, I figured the reason the difference between European and US options was due to standards.
I will see if I can find the standards back. They might be listed on the hitch supplier websites.
Physically, they are way different. The benefit of the Westphalia probably isn’t increased tow capacity, but in convenience. I went with an ecohitch due to cost and because 2” receiver parts are somewhat standardized/accessible in North America. My initial consideration for the Westphalia was increased tow capacity.
I believe the load required to fail the hitch mount itself is going to be a function of the cross-sectional area and grade of the bolts that are normal to the direction of travel. The bolts I have are grade 8 and around 5/8” in diameter, so my mental math has the shear at greater than 75,000 lbs since grade 8 is 150,000 lbs/in2. with that load, I’m not sure what the fuse is for failing a hitch.
When just driving down the road, there really isn’t that much of a load on the hitch. At least, not anything I think would make a difference between 2000 and 3000 lbs towed at a constant speed. The difference is how the unbraced trailer reacts to braking at 55 mph vs 70 mph, or at least that’s what the automotive standards believe.
for 2000/200 tow rating, I’m guessing most trailers are single axle. To pull 3000 lbs at 70 mph and have similar braking characteristics that the standards are trying to create, the tongue weight would probably need to be increased to at least 300-400 lbs. in that case, the overloading would cause the car to pitch upwards. To offset that, replacing the rear springs with something that can carry the additional load may be enough.
this is all way out of my area of expertise. I recommend following whatever load ratings are given by manufacturers.