Bob C wrote:

If you are towing a sailplane trailer at 75 MPH behind
a VW Passat, let me know where you're going, so I can
be sure to stay far away. IMHO, not nearly enough
tow vehicle mass, regardless of tires.

For what it is worth, the website for VW of Australia indicates that the
towing capacity for the VW Passat is 1300 km (2860 pounds) -- almost
twice the weight of a glider trailer (with glider). Of course, VW
doubtless does not use the same number in the US.