A single-wheel trailer has been designed and built to study the origins of tire noise and its basic characteristics. The single test tire, nominally the 10.00/20 size usually mounted on large trucks and semitrailers, is located 12.2 m (40 ft) behind the rear axle of the towing vehicle to isolate it from other noise sources. Reflective surfaces that could interfere with noise measurements are minimized by the high, single-beam construction of the trailer. The towing vehicle is modified to reduce its noise and wake in the vicinity of the test tire, which can be loaded to 22.2 kN (5000 lb) by dead weights and rolled at expressway speeds.Because of its unusual configuration, the dynamic behavior of the trailer was studied prior to design to help determine several design parameters and show that the trailer would follow well. Extensive stress analyses of the trailer beam and other structural elements were also required.The trailer has been built and operated, and adequately overcomes anticipated mechanical problems. A program of research into the mechanisms of tire noise generation which employs this trailer is now under way.