D.C. Mun. Regs. tit. 18, r. 18-2501
Except as provided in §§ 2501.2 and 2501.3, the total outside width of any vehicle shall not exceed eight feet (8 ft.).
Buses may have an overall width not to exceed eight feet, six inches (8 ft. 6 in.), if travel is restricted to a route approved by the Director.
Tractor-trailer combinations may have an overall width not to exceed eight feet, six inches (8 ft 6 in.), if the tractor-trailer combination travels on a route, street, road, or highway specified in § 2511.
No passenger vehicle shall be operated on any public District highway, street, or road with any load carried on the vehicle extending laterally beyond the line of the fenders on the left side of the vehicle or extending laterally more than six inches (6 in.) beyond the line of the fenders on the right side.
No vehicle which is higher than thirteen feet, six inches (13 ft. 6 in.), including the height of any load on that vehicle, shall operate on a public District highway, street, or road.
The intent and purpose of § 2501.5 is to regulate vehicle height only, and nothing in this title shall be construed to require the District government, any railroad, or any private corporation to do the following:
D.C. Mun. Regs. tit. 18, r. 18-2501