Sorry, I've been busy.

Many of the highway classifications are a routing hierarchy. They say little about type of road and more about the road's importance in the network. (I see the Michigan wiki page could use some clarification on this topic.)
motorway > trunk > primary > secondary > tertiary

I labeled only the section right off from the freeway as "primary", which anything off from a freeway could easily be.

You are welcome to change it.

We could also discuss it with others at the next monthly meeting.

I also have my eye on the road through Island Lake State Recreation area. The National Park Service says if it were in their parks, it would be a tertiary or secondary.
https://wiki.openstreetmap.org/wiki/US_National_Park_Service_Tagging:_Roads#Type_of_Road