heres the page from the orv guide book
ORV Operation on Other Lands
Roads, streets, and highways maintained for year-round automobile travel are closed to ORV operation, including the shoulder and right-of-way. (That is, the entire width between boundary lines of public ways maintained for vehicular travel is closed to ORVs.) However, ORVs registered as motor vehicles by the Secretary of State may be operated on the roadway.
Unless an ORV is licensed for highway use, it may not be operated on the roadway, shoulder, or right-of-way of a state, federal, or county road.
what I find funny is that they say its legal under the page before
ORV Operation on National Forest Lands
On all National Forests, motor vehicles can be used only on roads, trails, or areas that are designated as open. This includes all motorized wheeled vehicles from ATVs to street-legal vehicles.
I know it says national forests, but lots of county roads go through them. becarful as to not get tickets by knowing where you are.