43 C.F.R. § 2812.3-5
The use by the United States and its licensees of any of the rights received from a permittee hereunder shall be limited to that which is necessary for management purposes, or to reach, by the most reasonably direct route, involving the shortest practicable use of the permittee's road system, a road or highway which is suitable for the transportation of forest products in the type and size of vehicle customarily used for such purposes and which is legally available for public use for ingress to and the removal of forest products from Government lands or from other lands during such periods of time as the timber thereon may be committed by a cooperative agreement to coordinated administration with timber of the United States. However, the type and size of vehicle which may be used by the licensee on the permittee's road shall be governed by §§ 2812.3-7 and 2812.4-3 .
43 C.F.R. §2812.3-5