Hi Vstolpner,
The Westfalia Tow Bar I fitted is rated at 80Kg for the Tongue and 2000Kg for the Towing Weight (braked trailer). 1 Kg is about 2.2 lbs.
Other than small Box Trailers, most Trailers and Caravans in Europe are braked which means that the towing weights provided are much higher. The tongue weight limit is going to be much the same. I am guessing the US Towing Weight quoted is for an unbraked trailer ??
If you go on to the BMW site and build your BMW when it offers the option of a Tow Bar I think you will see the weights they provide. Doesn't seem to be in any BMW brochures or other descriptions. Most of the Tow Bar Companies do publish weight limits for their products.
I also found this page from a Car Leasing Company :-
http://carleasingmadesimple.com/busi...-weight-limit/