Winter Tire Tread Depth: When to Replace Them

Before the first snowfall hits Cambridge, Kitchener, Waterloo and Guelph, take a few minutes to check the tread on your winter tires. A winter tire grips snow with its deep grooves and biting edges, and as that tread wears down, the grip goes with it. Here's how much tread a winter tire really needs and how to check yours.

The number to remember: 4 mm

Transport Canada says that as a tire wears, it loses traction, and it advises against using tires worn close to 4 mm (5/32") of tread depth on snow-covered roads. In its words: don't use tires that have less than 4 mm of tread.

That's a stricter line than the tire's own wear bars. Michelin Canada explains that tread wear indicators are small raised ridges moulded into the bottom of the main grooves. When the tread wears down level with them, at 1.6 mm (2/32"), the tire has reached its minimum tread depth and has to be replaced. Transport Canada notes that some tires have 2 mm indicators, and that tires worn close to them have less traction and shouldn't be used on snow-covered roads or in severe snow.

So a winter tire can still be above its wear bars and already be past the point where Transport Canada says it belongs on snowy roads.

How to check your tread

1. Use a tread depth gauge. Michelin calls it the most accurate way to check, and it gives a reading in millimetres or 32nds of an inch.

2. Find the wear indicators. On Michelin tires, a small Michelin Man on the sidewall shows where they are. Other brands often mark them with a small triangle or "TWI". If the tread is flush with an indicator, the tire is done.

3. Check more than one spot. Michelin recommends measuring in several places across and around each tire, in case it has worn unevenly.

4. Don't judge from a standing height. Michelin points out that the tread pattern can still look well defined even when the grooves are worn down to the indicators.

Other signs it's time for new winter tires

Tread isn't the only thing to look at. Michelin Canada also recommends replacing a tire with cuts, cracks, bulges or blisters on the sidewall, and watching for longer braking distances or reduced grip. After five years of use, Michelin says tires should be inspected by a trained tire professional at least once a year, even if they look fine and haven't reached the wear indicators.

If only some of your tires are worn

Both Ontario and Transport Canada say to install winter tires in sets of four and not to mix different types of tires on one vehicle. Transport Canada adds that the tires with the deepest tread should go on the rear to help keep directional control, and that tires rotated regularly should have similar tread depth. Mixing tread patterns, internal construction or sizes makes your vehicle less stable.

It's also worth checking your pressure while you're down there. Transport Canada notes that tire pressure drops in the cold, so check it when the tires are cold, using the pressure on the tire information label on the edge of the driver's door or the door post.

Winter tires at SVS Tires & Wheels

If your winter set is near 4 mm, browse our winter tires or use the Find Tires by Size search to see options for your vehicle. On a budget? Take a look at our new economy tires. We never sell used tires. If you'd like a dedicated winter set that's quicker to change each season, ask about a wheel and tire package.

Still have plenty of tread? Book a seasonal tire swap and ask about tire storage for your summer set. Every install is balanced with Road Force balancing equipment, and we service TPMS sensors as part of every tire installation.

Visit SVS Tires & Wheels at Units 7-8, 990 Bishop St N, Cambridge, ON N3H 4V7. We're open Monday to Friday, 10:00 AM to 5:30 PM. Call 519-267-4200 or book online.

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Sources: Transport Canada, Using winter tires; Government of Ontario, Winter driving; Michelin Canada, Tire wear indicator; Michelin Canada, When to replace tires.