Basically they are unmaintained roads. Roads have a classification scale and that is the bottom of the barrel. They are different in every state and so is the legality of wheeling on them.
(1) Class 1 town highways are those town highways which form the extension of a state highway route and which carry a state highway route number. The agency shall determine which highways are to be class 1 highways.
(2) Class 2 town highways are those town highways selected as the most important highways in each town. As far as practicable they shall be selected with the purposes of securing trunk lines of improved highways from town to town and to places which by their nature have more than normal amount of traffic. The selectmen, with the approval of the agency, shall determine which highways are to be class 2 highways.
(3) Class 3 town highways:
(A) Class 3 town highways are all traveled town highways other than class 1 or 2 highways. The selectmen, after conference with a representative of the agency shall determine which highways are class 3 town highways.
(B) The minimum standards for class 3 highways are a highway negotiable under normal conditions all seasons of the year by a standard manufactured pleasure car. This would include but not be limited to sufficient surface and base, adequate drainage, and sufficient width capable to provide winter maintenance, except that based on safety considerations for the traveling public and municipal employees, the selectboard shall, by rule adopted under 24 V.S.A. chapter 59, and after following the process for providing notice and hearing in section 709 of this title, have authority to determine whether a class 3 highway, or section of highway, should be plowed and made negotiable during the winter. However, a property owner aggrieved by a decision of the selectboard may appeal to the transportation board pursuant to subdivision 5(d)(9) of this title.
(C) A highway not meeting these standards may be reclassified as a provisional class 3 highway if within five years of the determination, it will meet all class 3 highway standards.
(4) Class 4 town highways are all town highways that are not class 1, 2, or 3 town highways or unidentified corridors. The selectboard shall determine which highways are class 4 town highways.
(5) Trails shall not be considered highways and the town shall not be responsible for any maintenance including culverts and bridges.