What Is Meant By Average Tread Depth In Tires?

Tread depth is the vertical measurement between the top of the tire rubber and the bottom of its deepest grooves.

Average tread depth is the vertical measurement between the top of the tire rubber and the bottom of its deepest grooves when measured from different spots on the tire tread and then take the average of all the measurements.

In the United States, this is typically measured in 32nds of an inch, whereas millimeters are used in metric countries. The depth of a tire’s tread plays a critical role in maintaining traction and mitigating hydroplaning risks.

A new all-season tire generally boasts a tread depth ranging from 10/32 to 11/32 inches. In contrast, manufacturers design all-terrain tires with a deeper tread, varying from 11/32 to 19/32 inches.

How to Check the Tread Depth of a Tire?

Checking the tread depth of your tires is important for safety and legal compliance, as worn tires can significantly impair your vehicle’s handling and traction. Here’s how you can check the tread depth:

1. Penny Test

Take a penny and insert it into the tire tread groove with Lincoln’s head facing down. If you can see the top of Lincoln’s head, the tread is less than 2/32 inch. This means it is time to replace the tires.

2. Quarter Test

Similar to the penny test, but using a quarter with Washington’s head down. If you can see the top of Washington’s head, the tread depth is less than 4/32 inch and it’s time to consider replacing the tires soon.

3. Tread Depth Gauge

A more accurate method is to use a tread depth gauge, which is an inexpensive tool that you can purchase at an auto parts store.

Insert the probe into the tread groove, press the shoulders of the gauge flat against the tread block, and read the result.

4. Wear Bars or Treadwear Indicators

Modern tires have tread wear indicator bars built into them. These are small raised bars at the bottom of the tread grooves. When the tread wears down to the same height as these bars, it indicates that the tire has reached the legal limit and drivers should replace it.

In most regions, there is a legal minimum tread depth of 2/32 inches, but for safety, especially in wet conditions, many experts recommend replacing tires at 4/32 inches.

Always make sure to check several spots around each tire, as tires can wear unevenly. This will give you the average tread depth of the tire. If you notice significant uneven wear, it could be a sign of alignment, suspension, or inflation issues that you should address.

What Is the Optimal Tread Depth for Tires?

For safe driving conditions, the minimum recommended average tread depth is 5/32 inches. Tires measuring 4/32 inches or less usually require replacement. At 2/32 inches, they are bald and one should replace them immediately. The reason for these guidelines is primarily safety. As tread depth decreases, so does the ability to stop promptly on wet roads, and the potential for hydroplaning increases significantly.