Tread depth is the difference between stopping on wet Telegraph Road and sliding through the intersection. Here's the 30-second check.
Take a penny, Lincoln's head down, and stick it in a tread groove. If you can see the top of Lincoln's head, you're at or below 2/32" — legally worn out. Check three spots across each tire: outer edge, center, inner edge. Uneven results point to alignment or pressure problems.
The legal minimum is a dry-pavement number. Braking tests show wet stopping distance grows dramatically below 4/32", and in snow you want 6/32" or more. Our winters aren't a dry-pavement situation — plan replacement at 4/32", not the legal floor.
Cracked or bulging sidewalls, any tire over six years old regardless of tread (check the DOT date code on the sidewall), repeated slow leaks, or cords showing anywhere. A vibration that starts suddenly can mean a separated belt — get it checked immediately.
Rotate every 5,000–7,500 miles, keep pressures at the door-jamb number (check monthly in winter — pressure drops with temperature), and get an alignment yearly. Misalignment can burn out a new set of tires in under 15,000 miles.
Failed the penny test? Shop tires by ZIP code — live pricing at your closest of our nine shops, with financing if the timing's bad.
Nine shops across Southeast Michigan, free inspections, honest answers.