Many drivers still don’t realize the importance of checking their car tires regularly. Sadly, some only learn their lesson when an accident has already taken place.
Do not wait for the dreadful situation to come before you take action. On your own, you check the status of your car tires by measuring the tire tread depth.
You don’t need to follow any complicated procedures to do this. For starters, read below how to check tire tread with a penny.
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The Penny Test: A Step-by-Step Guide
The tread depth is a good indicator of a car tire’s life limit or age. The greater the tread depth, the better.
The rule stated in the United States is that the tire is subject to replacement when its tread depth reaches 2/32 of an inch or below.
Here we have a benchmark for a safe minimum tread depth. Unfortunately, you will need a fancy measuring device such as a Vernier caliper to measure anything below a quarter of an inch accurately.
Therefore, we should all be thankful that a penny exists because it will make this task much easier. All you need is to familiarize yourself with these easy-to-follow steps to perform the tire tread penny test.
Step 1: Locate The Critical Portions For The Tire Tread Coin Test
Check the tire ribs or the raised portions that encompass the entire circumference of the tire.
By inspection, you can tell which ribs have very shallow heights. These are the critical regions of your tire that would be subjected to the penny test.
Step 2: Insert Penny Into The Tire Rib With The Coin Upside Down
A penny coin has the face of Abraham Lincoln, which should play a huge part in this test.
With the head of the coin facing you, insert the penny into the tire rib upside down, with Lincoln’s head pointing downwards.
Step 3: Observe The Exposed Portion Of The Penny
The next thing to do is measure tire tread with a penny. Even though a penny doesn’t have exact marks for measurement, a good reference point to estimate 2/32 inches is the top of Lincoln’s head.
The distance between the edge of the coin and the top of Lincoln’s head should be close to 2/32 inches.
For easier inspection, you just need to check if Lincoln’s head is still visible after inserting the penny into the rib upside down.
- If it is, then the tread depth for that critical rib is less than 2/32 inches, failing the penny test.
- Our preferred result is to see the top of Lincoln’s head covered by a tire rib. This means that the tread depth is still acceptable with more than 2/32 inches depth.
Step 4: Perform The Penny Tire Tread Trick To Other Tires
If all the tire ribs have acceptable tread depth, then that tire passes the penny tire tread trick. Repeat the previous steps for the remaining tires of the car.
Is the Penny Test for Tires Accurate?
Keep in mind that using 2/32 inches as the minimum acceptable tread depth is conservative.
Other sources would suggest following the 4/32 tire tread percentage rule instead. Waiting for the tire tread depth to go down to 2/32 inches with a minimal tire grip might be too risky, especially when the road is wet and slippery.
It is also worth noting that a common tire wear indicator chart in the United States lists 1.66 mm as the legal limit for tread depth. While this quantity is close to 2/32 inches, the equivalent value of 2/32 inches in millimeters still falls short.
You can use the tire tread depth chart below as your guide.
Note that while the chart considers 2/32 inches as an acceptable limit based on the tire tread coin test, you should act accordingly once the tread depth reaches a certain measurement.
| 8 mm or 10/32 inches | Optimal |
| 7 mm or 9/32 inches | Optimal |
| 6 mm or 8/32 inches | Optimal |
| 5 mm or 7/32 inches | Acceptable |
| 4 mm or 5/32 inches | Acceptable |
| 3 mm or 4/32 inches | Inspect tread depth monthly |
| 2 mm or 3/32 inches | Nearing limit |
| 1.66 mm or 2/32 inches | Legal limit |
| 2.32 inches and below | Replace right away |
Can I Check Tire Tread with George Washington Penny?
Another emerging prevalent threshold for tread depth is 4/32 inches. It is a much less conservative estimate for a worn tire tread, so there is a higher guarantee of safety.
Now you might be wondering: is it accurate to check the tire tread depth with penny?
Remember that the basis of the penny test is the distance between Lincoln’s head and the coin’s rim, roughly 2/32 inches.
If you follow the 4/32 inches rule, then you can no longer use penny to check tire tread.
Instead, you will need another coin to estimate this new tire tread depth benchmark– a quarter, with your point of reference being George Washington’s head this time.
Conclusion
There are many ways to check the condition of your car tires, but to measure tire tread with a penny should be the simplest and least expensive. Some people might prefer a tire tread depth gauge to get more exact measurements.
However, the penny test is proven to be reliable, even without a gauge. You need good eyesight to inspect whether Lincoln’s head from the penny is still visible. Once you have already mastered how to check tire tread with a penny, you won’t need to buy pricey tools or learn complicated techniques for this.
