In the Metro Detroit area, there a ton of towing companies that use LTR trunking systems. Likewise, this is very common across the Lower Peninsula. It's very possible they might be using an SMR TRS. A little detective work goes a long ways in determining what radio band towing companies operate on.
The most common way to find out what radio band any commercial operator is on, is to examine the physical length of the antenna on the truck. Secondly, try to examine what type of radio is inside the vehicle. This can yield a lot of clues, and might tell the whole story. Finally, search all of the commercial two-way radio providers by frequency. This method would require a lot of time listening and attempting to decode what towing company you are listening to.
Happy scanning!
73s
Ron