Michigan doesn’t require winter tires, but your tires must be safe (no exposed cords, adequate tread, no “unsafe” condition). Using worn or unsafe tires can support an insurer’s or defendant’s comparative negligence argument. Winter tires clearly improve winter stopping distance (state safety guidance endorses them), but just having all-seasons isn’t negligence by itself. Keep good tread and proper inflation, and use chains only when conditions make them reasonably necessary. 

Studded tires are tightly restricted by rule; practically, manufacturers haven’t met Michigan’s pavement-wear spec, so they’re generally not used here.

‍