BLM rules and regulations for off-road vehicles and off-road vehicle areas are codified under…
§ 8340.0-5 Definitions.
As used in this part:
(a) Off-road vehicle means any motorized vehicle capable of, or designed for, travel on or immediately over land, water, or other natural terrain, excluding:
(1) Any nonamphibious registered motorboat;
(2) Any military, fire, emergency, or law enforcement vehicle while being used for emergency purposes;
(3) Any vehicle whose use is expressly authorized by the authorized officer, or otherwise officially approved;
(4) Vehicles in official use; and
(5) Any combat or combat support vehicle when used in times of national defense emergencies.
(b) Public lands means any lands the surface of which is administered by the Bureau of Land Management.
(c) Bureau means the Bureau of Land Management.
(d) Official use means use by an employee, agent, or designated representative of the Federal Government or one of its contractors, in the course of his employment, agency, or representation.
(e) Planning system means the approach provided in Bureau regulations, directives and manuals to formulate multiple use plans for the public lands. This approach provides for public participation within the system.
(f) Open area means an area where all types of vehicle use is permitted at all times, anywhere in the area subject to the operating regulations and vehicle standards set forth in subparts 8341 and 8342 of this title.
(g) Limited area means an area restricted at certain times, in certain areas, and/or to certain vehicular use. These restrictions may be of any type, but can generally be accommodated within the following type of categories: Numbers of vehicles; types of vehicles; time or season of vehicle use; permitted or licensed use only; use on existing roads and trails; use on designated roads and trails; and other restrictions.
(h) Closed area means an area where off-road vehicle use is prohibited. Use of off-road vehicles in closed areas may be allowed for certain reasons; however, such use shall be made only with the approval of the authorized officer.
(i) Spark arrester is any device which traps or destroys 80 percent or more of the exhaust particles to which it is subjected.