1. Check the tread wear bars
Tires have wear indicators molded into the grooves. When the bars become flush with the tread, the tire is at about 1.6 mm of tread depth and should be replaced.
2. Use the Canadian quarter test
The Government of Quebec recommends placing a 25-cent coin in a groove with the caribou’s nose pointing down. If you can see the caribou’s snout, the tire will have poor grip in deep snow. Check several grooves in different areas.
Useful tread-depth reference
Recommended for Quebec winter use
May be legal, but winter performance is reduced
Minimum tread-groove depth
3. Tread depth is not the only issue
Cracks, cuts, bulges, uneven wear, vibration or damage after a pothole impact can justify an inspection even if tread depth looks acceptable.
4. A tread-depth gauge is more precise
The coin test is a quick check. A proper gauge gives an exact measurement and lets you compare multiple areas of the tire.
Sources: Government of Quebec and Michelin Canada. This guide is educational and does not replace a professional inspection.