Penny Vs. Quarter Tire Test: Which Is Best For Measuring Tread Depth?

With the penny no longer in production here in the U.S., it begs the question: Is it going to get increasingly more difficult to do the penny test now? As the one-cent piece starts to dwindle, how else is a person supposed to do a quick at-home check of tire wear? As it turns out, there's another readily available coin that you can use. And it might even yield more useful results than the penny.

The quarter test is actually superior to the familiar age-old penny trick for the way it gives drivers more wiggle room before their tread has reached the minimum replacement point. The penny test can identify tread at about 2/32 of an inch, but the quarter test checks for roughly 4/32 of an inch. That's a whole extra sixteenth of an inch to work with. That could make all the difference for your tire performance, especially on wet roads where you'll want more than the tread minimum if you want to be safe. It's not a bad idea to embrace the quarter test going forward, both for the loss of the penny and the earlier warning the twenty-five-cent piece gives you.

The difference between the penny test and the quarter test comes down to Abraham Lincoln's head versus George Washington's head. For the penny test, you place a penny between the tread ribs with Abraham Lincoln's head pointing down. If the top of Lincoln's head is hidden by the surrounding tread, the tire has more than 2/32 of an inch remaining. If his entire head is showing, the tire has reached approximately 2/32 of an inch. That's the minimum replacement point according to the U.S. Department of Transportation and most individual state laws.

The quarter test uses George Washington instead, but the concept is more or less the same. With Washington's head pointed down and slotted inside a tread groove, as long as the top of his head disappears beneath the tread, you have at least 4/32 of an inch remaining. If his full head is showing, you should seriously consider replacing that tire soon. Sure, you're not at the legal minimum in most states, but your tire is still not operating at peak performance. For all intents and purposes, when a new tire has a tread of 10/32 of an inch or more, tires worn down to 4/32 of an inch have already lost a lot of their wet-weather performance. The quarter test just gives you more time to find the best deal on new tires before you hit the absolute minimum.