The Importance of Understanding Tire Tread Depth

Most car owners don't check their tires. Some that do, never check as frequent as they should, which should be once or twice a week, depending on how often the vehicle is used. Are you guilty of these bad habits?

Going over your tires on a regular basis is something you should do as a responsible motorist, because the condition that they are in plays a huge role in both your comfort and safety on the road. Sure, modern cars come with plenty of sophisticated safety features such as traction and stability systems, automatic emergency braking, lane keeping assist, etc., but they become of little to no use if your tires can't grip the road. And this is why constantly monitoring the condition and tread depth of your tires--as well as knowing the signs that say it's time to replace them--is of utmost importance.

What is tread depth?

Tread depth is the distance between the top of the tire’s rubber to that of its deepest grooves. Most brand new tires have around 8mm of tread depth, and once it reaches 3mm, that means it's time to replace your tires. You should never let your tires reach 1.5mm tread depth, as this indicates that they are grossly worn out. Should you continue to drive with less than 3mm tread depth, you put yourself and the lives of other people on the road at risk.

What's the purpose of tire tread depth?

Adequate tread depth plays a critical role in the tire's ability to grip the road. Especially when the road is wet, the tread pattern helps drive the water away between the tire and road surface, effectively preventing the vehicle form slipping and sliding out of control. Drivers with worn-out tires face longer braking distances, reduced maneuverability and grip, and an increased risk of hydroplaning during rainy and wet conditions.

How to measure tread depth

It bears repeating--you need to measure your tire's tread depth regularly to ensure your tires can still grip the road. There are a couple of ways you can accomplish this: First, by using a tread depth gauge, and second, by looking at a tire's built-in tread indicators. You can purchase a tread depth gauge at your local auto parts store or online. They are fairly easy to use: just press the gauge into the shallowest groove of the tire, push the shoulders flat against the tread, and then check the result.

Many tires have tread wear indicators--little bars spread across different locations around the bottom of the tread grooves. When the top of the tire's rubber becomes level with the surface of the tread wear indicators, your tire is ready for replacement.

The tread on your tires is crucial to your driving performance and comfort, with every groove, pattern, knob and shape serving a combined purpose. As the rubber on the tread wears away, so does the tire’s ability to keep you safe. Thus, monitoring your tire's tread depth regularly is a vital part of your duties as a car owner.