Measuring Tire Tread Depth

Your tires are one of the most important safety features of your vehicle, especially when driving in rain or snow conditions. However, many motorists rarely inspect the tires on their vehicle. Ensuring that you have the proper tread depth on your set of tires is an easy, yet important, way of ensuring your own safety when driving.

One of the main concerns of driving with insufficient tread depth is the tire’s inability to disperse water when driving on wet roads. When the groove depth is reduced, tires lose the ability to push water to the outside of the tire, leaving an excess amount of water between the road and the main contact point of the tire. This is known as hydroplaning, and it decreases the amount of control you have over your vehicle. A similar problem occurs when driving in snowy road conditions. Without the ability to condense the snow in the grooves and disperse it as they rotate, tires cannot effectively make contact with the road. The excess snow build-up between the tires and the road reduces traction, decreasing the control you have over your vehicle. To help minimize these risks, there are a few ways you can ensure your vehicle is operating with a safe tread depth.

The most accurate way to measure your tread depth is to use a tire tread depth gauge. The steps for operation are as follows:

  1. Insert the pin of the gauge into the shallowest groove of the tread until the base of the gauge is flush with the tire

  2. Read the scale


Please reference the chart below to better understand what your tread depth scale means:

Tread DepthAction
6/32"Your tires have sufficient tread depth
5/32"Consider replacing your tires if wet road conditions are a concern
4/32" to 3/32"You should consider a tire replacement or monitor closely
2/32" (1.5mm)Your tires are considered legally bald and need to be replaced

Another way of measuring your tread depth is by using a traditional Canadian penny.  The penny test is conducted by placing a penny in the tire groove with the Queen’s crown facing down.  If you can see the top of the Queens crown, you need to replace your tires.  If you use an American coin and can see the top of Lincoln’s head, you need to replace your tires.

On an ongoing basis, you can monitor your tires tread wear indicators. Tread wear indicators are small raised bars that expand across the grooves of the tire tread to mark the minimum amount of tread depth allowed. There are typically six tread wear indicators that can be found dispersed across each tire. Once your tire tread has worn to the level of the tread wear indicaftors, you need to replace your tires.

As a general rule, tires should be replaced if they have any deep cuts, slits, cracks, blisters, and/or bulges, as they may be unsafe for operation.