Speed limits the same as posted for that road if you are in a ditch. Trail speed limits are safe and prudent. There are 146 of groomed trails in Ohio. Trail permits are not required for out of state snowmobilers. Helmets are required for everyone.
Roads are open to snowmobiles if decided by local authorities only.
Same rule apples for riding road shoulders. Road ditches are not open. There is no posted speed limit. There are 6,200 miles of groomed trails in Oregon. There are 2,000 miles of groomed trails in Pennsylvania.