Did they increase the allowed speed on the side of the roads ? I thought it was just 20 MPH max.
In general the speed limit is 25mph on the sides of public roads, there can be some sections that are lower....ie. through some towns, Newberry comes to mind, they set a 15mph limit on city streets. In 2008 the State of Michigan passed a law to allow counties to decide for themselves if they wanted to allow ORV's on public roads, it started with the UP then was amended a few times since to add counties in the LP. At the moment the northern half of the LP is open, there has been discussion to add the rest of the state but I do not know if it has passed yet. The rule of thumb used to be, in the UP it was open unless posted closed, in the LP it was closed unless posted open but as of Jan 2018 the state has opened another 6300 miles of forest roads in the northern LP. The links below should give you an idea of open areas.
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Public Act 240 of 2008 enabled counties and townships in Michigan to allow ORVs to travel upon roads under the their jurisdiction. Each has to enact an ordinance allowing for this, else their roads remain closed to ORVs. Subsequent legislation has granted this power to all counties within the State."
Here is the DNR site about ORV's, some good info
DNR - ORV/ATV Riding
This is the ORV ordinance for my county, most counties are similiar
https://www.mackinaccounty.net/wp-content/media/orv-ordinance.pdf
https://www.mackinaccounty.net/wp-content/media/orv-ordinance.pdf
VVmapping has a link to most county ordinances, they also sell maps & GPS software, I have it for my snowmobiles & P5, I highly recommend it.
MI County Road Info - VVMapping.com