On average, Americans spend nearly $100 a month on the maintenance of a new car. These include tire replacement. A moderately-priced one may be worth $150, and you’re likely to change four of them at once.

Ideally, whether your vehicle needs repair or maintenance, the best option is to bring it to a mechanic from the closest reliable shop near your area. If it’s still under warranty, you can let the dealership handle it.

But on both occasions, car owners are likely to spend money. For this reason, some go the DIY route when checking tires. Probably the most popular technique is the penny test.

The question is, does this work? When is the best time to avoid doing it?

What Is the Penny Test?

No one knows for sure the history of the penny test, but it’s been around for years. The simple technique of measuring tire tread depth has also been tested and recommended by vehicle owners and even automotive experts.

One thing is for sure. The penny test, which uses the Abraham Lincoln coin, came about when the Department of Transportation (DOT) set the minimum depth of tire treads to 2/32 inches.

Why is it important to determine the depth of the tire tread? Tires, like every other part of a vehicle, get worn. Consider the roads they pass through and the mileage a car owner covers throughout the vehicle’s lifetime.

Worn tires, though, can significantly increase the risks of vehicle accidents. It lessens the friction between the car and the road. A vehicle can skid or cannot stop immediately even when the driver presses hard on the brakes.

Incidentally, the distance between Abe’s head and the tip or edge of the coin is exactly 2/32 inches. This means that if one inserts it into the treads and can see much of the head, the tire must be significantly worn. It’s time to replace them.

Does This Work?

Several say yes, but others also want to add a few caveats and warnings:

  1. The Penny Test May Not Be Ideal to Those with Limited Tire Knowledge

A tire usually has five primary components, such as the ribs, blocks or lugs, voids, and grooves. Although they may seem to look the same, they may vary in terms of tire tread patterns. Some are asymmetric, while others are directional and symmetrical.

The problem comes in when car owners are not familiar with these pieces of information. In fact, in a study among 2,000 vehicle owners in the country, a whopping 68% didn’t know their car had at least one issue.

In another survey, this time by Cooper Tires, 25% didn’t know anything about vehicles. About 30% said they couldn’t change a tire.

  1. The Quarter Test May Be a Better Option than a Penny Test

What’s the quarter test? It works similarly to the penny test, except the car owners have to use the coin that features George Washington. This will help measure the tire tread depth at 4/32 inches. If one can already see Washington’s head, then tire replacement must be next on the agenda.

Now, why should a car owner change tires when they’re still some good depth left? Other automotive experts argue that what the DOT gave was only a minimum limit. In other words, one doesn’t really have to wait until their tire tread depth is at this measurement before they change the tires.

Moreover, a famous Auto Week article highlighted how replacing the tires at 2/32, and 4/32 inches can spell a huge difference in safety.

In the video, they performed driving tests using various tires: new ones with 10/32-inch tread depth worn tires with tread depths of 4/32 and 2/32 inches.

In the tests, the vehicle traveled in the rain. When it wore new tires, it could stop at almost 200 feet. When they changed it to 4/32, the vehicle moved for 95 feet more before it stopped.

Lastly, when they used the worn tire with 2/32 inches of depth left, as measured by a Lincoln, the car not only skidded for 400 feet before it stopped but also traveled at 44 miles per hour.

Is the penny test accurate? Anecdotes say they do, but tire tread depth is not the only concern of a vehicle owner.

More often than not, the benefits outweigh the costs if only owners choose to bring their vehicles to the dealership or a mechanic shop for repair and maintenance.

These places do more than measure tire tread depth. They can check other parts of the vehicle, perform repairs when needed to avoid further damage, and offer recommendations to boost one’s safety on the road.