Why Optimum Tread Depth Is Important On Winter Tires

Tread depth is essential for displacing rainwater, slush, and clawing into the snow while driving during winters. With usage, tires wear out, and tread depth decreases, leading to a decline in the performance of the tires. This can also lead to reduced snow traction, decreased acceleration, and increased stopping distances. Depending on the type of tires, the tread depth can range between 7mm and 9.5mm. Although the legal depth might differ based on provincial winter tire laws in Canada, it is safe to replace your winter tires with tread depth below 4mm. When the tread level on your winter tires falls below 4mm or the recommended limit, the risk of hydroplaning increases on wet surfaces. Hydroplaning happens when the tires can not expel the water away. This causes a film of water to form between the tire and the road, which reduces the traction and dramatically hampers the steering and braking of the vehicle. 

A test conducted by Consumer Reports states the importance of tread depth in dispersing rainwater, slush, and clawing at the snow; the tests result indicate a major decline in the performance of tires when half of the tread depth is left. Tires with 50 percent (4 to 4.5 mm) of tread depth remaining showed a 14 percent decline in snow traction, 8 percent loss in hydroplaning resistance, 7 percent loss in wet braking, and a significant loss in braking ability on the ice.

Tires are usually provided with built-in tread wear indicators which help you ‌identify the degree of wear so you can carry out a timely replacement. The tread indicators are small raised bars located evenly between the main grooves of the tire. Several winter tires are equipped with these indicators and they help you identify whether your tire treads are worn out or not. Once these tire wear indicators are level with the tire tread and begin to wear, then the tire must be replaced. These wear bars are placed all around the tire at different points that also help you ‌spot uneven tire wear.

Tire tread depth gauge is a very useful tool to check the life left on your tires. To use it, simply insert the probe into the treads of your tire and push the gauge enough so it sits flush with the tire. The gauge will show a reading, which will indicate the tread depth of the tire. While checking tires for tread depth, ensure to check in various spots because a misaligned wheel can result in uneven tread wear. Always judge the tire's tread depth by the lowest depth measured. If the gauge reads 4mm or less, you need to replace your winter tires, as they are not safe for snow and winter driving.

A classic method to check your tire's tread depth is by inserting a quarter into the groove of your tires. Take a 25¢ Canadian coin and insert it into the groove with the caribou facing downwards. If you can see the nose of the caribou, it means the tread depth is shallow and calls for a replacement. If the coin sits deep into the treads and you can't see the caribou's nose, your winter tires are in good condition.

Several factors can affect the lifespan of your winter tires. Therefore, if you want your tire treads to last long, proper tire maintenance is recommended. Following handy tips can make your tires go the distance and keep you safe on the road.

• Always ensure your tires are inflated to recommended pressure levels mentioned in the owner's manual or on the label attached to the lower part of your door frame. Maintaining proper tire pressure can reduce tread wear and increase mileage. Most vehicles today are equipped with Tire Pressure Monitoring System (TPMS) that alerts the driver when the tire pressure falls too low. As a part of your tire inspection routine, ensure your TPMS sensors are functioning properly.

• To ensure longer life of your tires, get your wheels aligned whenever you notice uneven tire wear or your vehicle is pulling to the right or left. It's recommended to get your wheel alignment checked twice a year to ensure your wheels are pointing straight. Often driving too hard over a pothole, a curb or a parking block can lead to wheel misalignment.

• On a front-wheel-drive vehicle, front tires are subjected to more wear compared to rear ones. The opposite is true for rear-wheel-driven cars. Therefore, you should rotate your vehicle’s tires every 10,000 km to prevent uneven tire wear. This helps to even out the wear on all tires and makes them last longer. If you have directional tires, then the tire must be switched with the one on the same side (front right tire switched with rear right tire). However, if you have non-directional tires, then the tires can be rotated in an X-pattern (front left tire switched with rear right and rear left with front right tire).

To ensure increased control and safety, you should have winter tires on your 4WD vehicle as well. A four-wheel-drive (4WD) vehicle is not a substitute for traction provided by tires, and in order to achieve better handling and maneuvering, winter tires with optimum tread depth are necessary. We also recommend you stick to winter tires that are marked with the “Three Peak Mountain Snowflake” symbol on the sidewall. This symbol indicates that ‌the tire meets winter performance requirements set by Transport Canada. However, some tires are marked M+S (mud and snow) that may not provide adequate grip in severe winter conditions. You can check our winter tires buying guide which will help you make a better decision while choosing new winter tires for your vehicle.