This should answer your question as well as licensing:
b. All Terrain Vehicle Permit Required. All Off-Road Recreational Vehicles
(ATVs, dirt bikes and out-of-state ORVs displaying a permit or registration
from their state) are required to display a Wyoming ORV permit while
operating on public lands and other designated trails or areas (excludes
private property) within Wyoming. ORVs may only be operated upon
public lands when on roads, trails or areas designated ?open? by
appropriate local land managers (Forest Service, BLM or others, as
appropriate). ORV riders should contact the local land manager?s office
in the area in which they wish to ride to determine which roads, trails and
areas are open for ORV use. Visit
http://wyotrails.state.wy.us for phone
numbers of the various land managers in Wyoming. The $15.00 annual
ORV permit is available at most local ATV/ORV dealers and selling agents
throughout Wyoming or by calling (877) 996-7275. Please allow 7 to 10
days delivery. Major credit cards accepted.