Photo: J.J. Gouin (Shutterstock)
As you were learning how to drive, you may have also learned a few car maintenance basics, like how to refill your windshield wiper fluid or check your oil levels. Another common tip was to use a penny to check the tread on your tires.
But like everything else, the cost of this simple test has also gone up over the years. Now, instead of using a penny, many automotive experts recommend using a quarter for this check. In an article for TheDrive, Tony Markovich explains how to do this, and why the quarter replaced the penny for this classic hack. Here’s what to know.
What is tire tread and why is it important?
In short, the outside part of a tire—as in, what touches the ground—is known as the tire tread, and it, Markokvich says, “is usually cut in a pattern of grooves and ridges.” The tread is important because it’s how a vehicle grips the road as it is driving.
As the grooves and ridges wear down with use, they become less effective at allowing the vehicle to maintain traction during inclement weather—especially if precipitation is involved. That’s because the treads help keep the car in control when roads are slick, and reduce the chance of hydroplaning.
Why the quarter has replaced the penny
Given the importance of tire tread, drivers are encouraged to check it regularly—and traditionally, this has been done using a penny (Michelin still endorses this rule today).
Basically, you stick an upside-down penny in one of the ridges as the lowest point of the tire, and if you can see the top of Lincoln’s head, then it’s time to change the tire. “This rule operates under the impression that 2/32 of an inch is the limit of an operational tire,” Markovich writes.
Meanwhile, some experts have questioned this rule for decades, and now some companies, organizations, and publications—like AAA and TheDrive—now recommend using a quarter instead of a penny.
“This rule operates under the impression that 4/32 of an inch is the safe limit,” according to Markovich. “When it comes to tire safety, we prefer to stick to the side of caution, so we use the quarter test.”
How to check tire tread using a quarter
Finally, here’s Markovich with step-by-step instructions on how to check tire tread using a quarter:
Find the most worn or lowest point on the tire.With a quarter upside down and with Washington’s head facing you, place the quarter in between the tire’s tread. If the top of his head is still buried, then you’re good, for now.If you can see the top of his head, then it’s time for new tires.And while you’re down there, don’t forget to routinely check your tire pressure along with their tread.
