There are many designated snowmobile trails and corridors across the state. In order to use them, you will need a snowmobile trail pass and display it on your sled. Most trails open in mid-December. Check the Travel Wisconsin website (https://www.travelwisconsin.com/snowreport/snowmobile) for trails and conditions before you go.
Check out these Ellsworth, WI ATV/OHV resources: