This SAE Information Report establishes a consistent procedure for measuring and analyzing the natural sway response of a particular trailer when attached to a particular vehicle under specific loading and operating conditions. This test procedure applies, but is not limited to, passenger cars, vans, light/medium-duty trucks as tow vehicles, and semitrailers with a Gross Vehicle Weight Rating (GVWR) of 11794 kg (26000 pounds) or less. Other applications include full trailers, tow dollies, tow bars, and the like. Other articulated vehicles can utilize this test procedure as long as the test does not exceed the linear behavior of the system. This test procedure does not apply to motorcycles towing trailers.