Bridgestone Team | 5 min read 

Keeping your tires in top condition is about more than just convenience—it’s about caring for what really matters: your safety, your family, and everyone you share the road with. This guide explains how to check tire tread depth, including the easy penny test for tires, helping you feel confident on every drive no matter what the road brings.

Tire tread is the patterned part of your tire that makes direct contact with the road. Understanding its parts can help you know how to check tire tread and recognize when tires need replacing.

When it comes to checking tire tread, there are a number of methods that can help you know if it’s time to replace a tire. Heavily worn tread will prevent a tire from performing as designed and can lead to unsafe driving conditions. One of the simplest, most common ways to check tread depth requires nothing more than a penny and a few moments of your time.

In the United States, tire tread depth is measured in 32nds of an inch. New tires typically come with 10/32” or 11/32” tread depths, and some truck, SUV and winter tires may have deeper tread depths than other models. The U.S. Department of Transportation recommends replacing tires when they reach 2/32”, and many states legally require tires to be replaced at this depth.

The idea of the penny test is to check whether you’ve hit the 2/32” threshold. Here’s how it works:

1. Place a penny between the tread ribs on your tire. A “rib” refers to the raised portion of tread that spans the circumference of your tire. Tire tread is composed of several ribs.
2. Turn the penny so that Lincoln’s head points down into the tread.
3. See if the top of his head disappears between the ribs. If it does, your tread is still above 2/32” , If you can see his entire head, it may be time to replace the tire because it has reached the end of its useful life.

When performing the penny tire test, remember not only to check each tire, but to check various places around each tire. Pay special attention to areas that look the most worn. Even if parts of your tread are deeper than 2/32”, you should still replace the tire when any areas fail the penny test.

Consistent wear around the whole tire is normal, but uneven tread wear could be a sign of improper inflation, wheel misalignment, or a variety of other things. If you see uneven tread wear, you should have a technician inspect your vehicle.

The quarter test is a quick way to see if your tread is above or below 4/32”, a depth that’s vital for safe stopping in wet weather.

1. Insert a quarter into the tread groove, Washington’s head down.
2. If the tread covers part of Washington’s head, you have at least 4/32”. If you can see all of Washington’s head, your tread is dangerously shallow for wet conditions.

Why 4/32”? Tests show that below this level, wet-weather stopping distances increase and the risk of hydroplaning rises dramatically. Begin planning for new tires when you hit this mark!

A simple way to check your tire tread depth is by using a tread depth gauge. You can find tire tread depth gauges at your local auto parts store. There are many models available, but an inexpensive simple graduated probe gauge will work just fine. All you have to do is stick the probe into a groove in the tread and press the shoulders of the probe flat against the tread block and read the result. All gauges should measure in both 32nds of an inch and millimeters.

1. Digital Gauge: Turn on, place the tip in the groove, and read the digital display.
2. Probe-Style: Insert probe fully into the lowest tread groove, press base flush, and record the marking.
3. Tip: Check inner, center, and outer edges of the tire, then average for accuracy.

Another indicator of worn out tread already lives in your tires themselves. Every performance, light truck, or medium commercial tire comes equipped with indicator bars (or wear bars) embedded between the tread ribs at 2/32”. They’re there to help you monitor tread depth and make decisions about tire replacement. Just look to see if the tread is flush with the indicator bars. If they are, it’s time to replace the tire.

While the penny tire test does deliver on what it promises – indicating whether tread has reached the legal limit – it may not be the best indicator of whether your tires are safe for the road. Tire performance can diminish significantly before your tread hits 2/32”. Even tires that meet the minimum legal requirement may not prevent you from hydroplaning or losing control in rainy, slushy conditions. If you think your tires may be close to needing replacement, have them checked out by a licensed mechanic.