32 C.F.R. § 634.25
(a) Installation or activity commanders will establish a traffic code for operation of motor vehicles on the installation. Commanders in overseas areas will establish a traffic code, under provisions of this part, to the extent military authority is empowered to regulate traffic on the installation under the applicable SOFA. Traffic codes will contain the rules of the road (parking violations, towing instructions, safety equipment, and other key provisions). These codes will, where possible, conform to the code of the State or host nation in which the installation is located. In addition, the development and publication of installation traffic codes will be based on the following:
(b) The installation traffic code will contain policy and procedures for the towing, searching, impounding, and inventorying of POVs. These provisions should be well publicized and contain the following:
(c) Installation traffic codes will also contain the provisions discussed as follows: (Army users, see AR 385-55).
(1) Motorcycles and mopeds. For motorcycles and other self-propelled, open, two-wheel, three-wheel, and four-wheel vehicles powered by a motorcycle-type engine, the following traffic rules apply:
(2) Restraint systems.