A tire tread is composed of ribs or grooves throughout the circumference of the tire. This raised portion of the tread expels water making the vehicle safe to drive under difficult weather conditions such as rain and snow.
However, when the tire tread wears down, it loses traction on the road and forces the braking and steering system to work harder especially on wet conditions. It becomes unsafe to drive when the tire tread depth reaches 2/32 inches.
But, how to check tire tread depth? Tire tread depth can be measured using a penny, a quarter, a tire tread wear indicator, or a tire tread depth gauge.
Table of Contents
Ways to Check Tire Tread Depth
1. With a Penny
In the US, you can measure tread depth on a tire using a penny.
Insert the penny to the tire groove with Abraham Lincoln’s head going in first.
- If you can see all of Lincoln’s head, it means that the tire’s tread depth is below 2/32 inches.
- If you have the same result when you check several grooves of the tire, tire replacement is inevitable.
- If a small part of Lincoln’s head hides in the groove, it is safe to assume that your tire’s remaining tread is 4/32 inches.
Some recommend replacing tires as early as this tire tread depth measurement because of diminished vehicle performance. The tires may not survive harsh driving conditions.
2. With a Quarter
Another way to check the tread on your tires is using a quarter test.
In this test tread on tires, the tire’s tread depth is measured using George Washington’s head.
- The tires are safer to drive if Washington’s head was covered entirely or not visible when placed in between tread grooves. This is typical with new tires having 10/32 to 11/32 inches or 8 to 9 millimeters.
- If Washington’s head touches the rib of the tire when you insert it facing down (visible to you), the tires are still safe with 4/32 inches tread left.
- If the quarter shows Washington’s head clearly, the tire tread depth is less than 2/32 inches. This calls for immediate tire replacement.
Conducting a penny test or checking tire tread with a gauge can reassure you that you measure tire tread correctly.
3. With A Tire Tread Wear Indicator
You can also check wear on tires without any tools because tires have a built-in tire tread indicator or wear gauge.
They can be seen as six bars throughout the tread ribs. The bar becomes visible as it reaches the minimum legal tread depth of 2/32 inches or 1.6 millimeters.
Some tires were designed with different grades of bar, such as 8/32, 6/32, 4/32, and 2/32. So check all the tread grooves to make sure it follows the tire wear indicator chart.
The tire tread depth of brand new tires of pickup trucks or large vehicles is around 15/32 to 20/32 inches.
4. With A Tire Tread Depth Gauge
If you would like to get a precise tire tread depth measurement, use tire tread depth gauge.
Of course, this tool cannot measure a bald or totally worn-out tread.
Look for the lowest tread depth. Insert the gauge pin into the groove, then press it towards the tread. This tool provides exact readings in inches and millimeters. They can be purchased in automotive shops for around $4.
What to prepare: Penny, Quarter, Tire Tread Indicator or Tread Depth Gauge
- Penny – a quick coin test used to check if the tire tread depth is on the 2/32 inches threshold.
- Quarter- another coin test that can tell if the tires are in good shape at 4/32 inches.
- Tire Tread Indicator refer to the rubber notches that are raised to 2/32 inches. When the indicators are flushed, it means the tires are worn out to an unsafe level.
- Tread Depth Gauge provides the most accurate tire tread depth measurement.
Detailed Steps for Each Way
The Penny Test
- Grab a penny. Use Abraham Lincoln’s side.
- Turn the coin upside down with Lincoln’s head pointed towards the tread groove.
- Thrust the penny in between the tread of the tire.
- Check if Lincoln’s head is visible. If it is, the tires are unsafe to use because the tread is shallow than the minimum tread depth.
If a part of Lincoln’s head disappears in the groove, the tread is still above 2/32 inches.
- Do this test throughout the tire. Check various places, especially the areas that look worn out.
The Quarter Test
- Get a quarter. Use George Washington’s side.
- Insert the quarter with Washington’s head thrusted towards the ribs of the tire.
- If you can see Washington’s head, the tires need replacement.
If the tread covers Washington’s head, the tires are safe to use at 4/32 inches deep.
- Conduct this test in multiple areas in the tire. Pay attention to areas that are visibly worn out.
Tire Tread Wear Indicator
- Look for the initials TWI (Tread Wear Indicator) on the shoulder of the tread.
- Right across that point, you’ll find the tread wear indicators or bars at the bottom of the tread.
- If the tread is flushed or exposed the same level as the wear bars, they are considered unsafe or worn out.
- Some tires have numbers at the center of the tread rib that indicate the tread depth in millimeters. As the tire wears down, these numbers fade. The visible number when you check the tire indicates the tread left.
Tire Tread Depth Gauge
- Check the measuring scale you are going to use (inches or millimeters).
- Place the tire tread depth gauge on top of a groove of the tire.
- Push the gauge.
- Rotate the scale until you find a number with a line below it.
- The first number that appears is the tire tread depth measurement.
When is the Best Time to Check Tire Tread Depth?
In general, tire tread depth should be checked every 3,000 miles or 5,000 km. It is also recommended to check the tread on tires seasonally or during changing of winter or summer tires.
Conclusion
Keeping a close check on your tire’s health is possible if you know how to check tire tread depth.
You can measure the tire tread depth with or without a gauge. The coin tests are helpful in providing an estimate of tire tread depth. However, if you would like to prevent vehicle accidents, the best way to check tread on tires is by using tire tread depth gauge.
The standard minimum tire tread depth is 2/32 inches but it is safer to plan tire replacement as soon as they approach 4/32 inches deep.
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