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How to Check Tire Tread Depth: The Penny Test, Quarter Test and More

Discover the simple yet effective techniques like the Penny and Quarter Tests to accurately measure your tire tread depth for safer driving.

How to check tire tread depth

Tire tread depth is a crucial aspect of vehicle safety, yet often overlooked. Ensuring that your tires have adequate tread is vital for maintaining grip on the road, especially in adverse weather conditions. This article provides a comprehensive guide on how to check tire tread depth, including the minimum required depth, and various methods such as the Penny and Quarter Tests, Tire Tread Wear Indicators, and the use of a Tread Depth Gauge.

What is the Minimum Required Depth?

In 42 of the 50 states, the minimum legal tread depth for cars is 2/32 of an inch. In California and Idaho, 1/32 is the legal minimum. Arkansas, Montana, New Mexico, North Dakota, South Carolina and West Virginia have no standards on tread depth. Texas makes things more complicated by requiring 3/32 for a vehicle to pass inspection, yet only requires 2/32 to be on the road.

The reason why most states require a minimum tread depth for car tires is because bald tires can significantly increase the risk of hydroplaning or losing control, particularly on wet or slippery surfaces. It’s important to regularly check your tires to ensure they meet this minimum standard.

The Penny Test

The Penny test for tire

One of the simplest ways to check your tire’s tread depth is the Penny Test. This test involves inserting a penny into the tread grooves of your tire. Place the coin with Lincoln’s head pointing downwards into the tread. If you can see the top of Lincoln’s head, it’s time to replace your tire as the tread is less than 2/32 of an inch. 

The Quarter Test

For those seeking a more conservative approach, the Quarter Test offers a higher safety margin. Similar to the Penny Test, insert a quarter into the tread grooves with Washington’s head facing down. If the top of his head is visible, your tread depth is less than 4/32 of an inch. While this is above the legal minimum, it’s a good indicator that you should start considering new tires.

Tire Tread Wear Indicator

Tread Wear Indicator on a Tire

Most modern tires feature built-in Tread Wear Indicators (TWIs). These are small raised bars that run perpendicular to the tread. When the tire’s tread is flush with these bars, it means the tread depth has reached 2/32 of an inch, indicating that the tire needs to be replaced.

Measuring with a Tread Depth Gauge

For the most precise measurement, a tread depth gauge set allows you to measure your car tires’ thread depth in 2 different ways: analog and digital. In this set, a brake lining thickness gauge is included too. 

These inexpensive tread gauges are equally simple to use: insert the probe into the tread groove and press the shoulders of the gauge flat against the tread. The reading will show the depth of your tread in 32nds of an inch. If the two different gauges measure the same tire depth, you are 100% sure the reading is correct.


Regularly checking your tire tread depth is a simple yet essential part of vehicle maintenance. It not only ensures your safety but also helps in maintaining optimal vehicle performance. Whether using a penny, a quarter, built-in indicators, or a gauge, keeping an eye on your tire tread depths is a proactive step towards safer driving.

Be safe out there!

Happy cruisin’!


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