Your tires are the only part of your vehicle that make direct contact with the road — and it’s the tread that gives them grip. Worn-out tread reduces traction, increases stopping distances, and raises the risk of accidents, especially in wet or snowy conditions.
Here’s everything drivers should know about tire tread depth, why it matters, and how to check it.
Tire tread depth is the measurement from the top of the tread rubber to the bottom of the tire’s deepest grooves. In simple terms, it’s the amount of “grip” your tires have left.
New tires typically start with about 8–10 mm of tread depth.
Ontario’s legal minimum is 1.5 mm — but your tires lose much of their effectiveness long before that.
Recommended safe replacement: Most experts suggest changing your tires once tread depth drops below 3–4 mm, especially before winter.
Safety in Wet Conditions
Deeper tread channels water away from the tire, reducing the risk of hydroplaning. Shallow tread can’t move water effectively, making it harder to stop or steer.
Winter Performance
In snowy or icy conditions, tread depth helps your tires “bite” into the surface. Worn tires slide more easily and lengthen stopping distances.
Everyday Handling
Good tread provides better grip for acceleration, cornering, and braking, giving you more control behind the wheel.
You don’t necessarily need special tools to measure tread depth — a simple coin or a tire tread gauge will do the job.
The Quarter Test: Insert a quarter into the tread with the caribou’s nose pointing down. If you can see the nose, your tread is too shallow.
Built-In Wear Bars: Many tires have tread wear indicators — small rubber bars that appear across the grooves when the tread is worn down.
Tire Tread Gauge: For the most accurate reading, use a tread depth gauge (available at most auto shops).
If your tread is below 3–4 mm, it’s time to start shopping for replacements. Even if you haven’t hit the legal limit, driving with worn tread compromises your safety — especially in poor weather.
💡 Always check all four tires. Uneven wear could signal alignment or suspension issues that need attention.
Tread depth and tire pressure go hand in hand. Proper inflation ensures the tread makes even contact with the road, preventing uneven wear. Conversely, low or high tire pressure can shorten tread life.
👉 Related read: Check out our blog on Tire Pressure Explained to keep your tires performing their best.
Your tread depth is one of the simplest — and most important — safety checks you can do. Regularly measuring tread ensures your tires are ready for rain, snow, or sun and helps prevent costly repairs or accidents down the road.
When in doubt, visit a trusted tire professional to have your tread depth measured and get advice on replacement options.
Need help on the road? Our Roadside Assistance team is always just a call away.