You may have heard of the penny test for tire tread depth and wondered if it’s something a layperson can manage, and a reliable test and indication of tire tread depth.
The answer to both is “yes!” If you have a penny handy this is an evaluation anyone can manage, and as far as rudimentary tire tread measurement goes, the penny test is about as reliable as it gets.
Before getting into details, note that if you want to be more accurate in measuring your tire tread depth we highly recommend a tire tread gauge, which is also very straightforward and economical. Read how to use a tire tread gauge for more information. However, as a starting point, and to let you know approximately where you stand (if your tires are still suitable for use), the penny test does the trick.
Insert the penny into the tire tread grooves upside down so the top of Old Abe’s head is heading into the groove.
Be sure to insert the penny into various tread grooves across (left to right) and around the tire. You should check in multiple tread grooves and in multiple locations to allow for uneven wear across and around the tires, which is not uncommon.
If some of Lincoln’s head is covered by the tread, then you have at least 2/32" of tread remaining, which is minimum tread depth. If none of Lincoln’s head is covered by the surrounding tread when the penny is inserted into the tread grooves, then you’re below minimum and it’s definitely time to replace your tires.
Important: Your lowest tread measurement should be your reference point. If any of the tread grooves are below minimum tread, then it’s advisable to replace. Sufficient tread depth in one area of the tire doesn’t compensate or cover for insufficient tread depth elsewhere on the tire.
If the top of the Lincoln Memorial is covered, then you have more than 2/32" of tread. For most normal driving contexts and applications, that’s plenty of tread life remaining.
If the penny test demonstrates that you’re clearly over 2/32" tread depth and you’d like to know more about what your actual tread depth is, then dig deeper into that piggy bank and grab a quarter…
Insert the quarter upside down so that the top of Washington’s head is heading into the tread groove.
If some of Washington’s head is covered by the tread, then you have at least 4/32" of tread remaining.
Pass the quarter test with flying colors as well? Then you’re in pretty good shape. If you haven’t lost the penny and are having fun, there’s one more test… Turn the penny around so that the Lincoln Memorial is facing you. Once again, insert the penny upside down so that the top/roof of the Lincoln Memorial is headed into the tread groove.
When evaluating your tire tread depth, don’t forget that wear bars are conveniently found on all street tires. The tire wear bars run laterally (left to right) across the tread grooves on your tires. Along with the initial penny test described above, the wear bars are an indication of 2/32" tread remaining, i.e. when the tread bars are even with the surrounding tread, then it’s time to replace tires.
Keep in mind that even if your tires have more than the minimum 2/32" of tread depth remaining (or even 4/32"), that’s not reason to put your tire situation to back of mind and move on. Tire tread depth is critical to driving safety in a variety of road conditions. Consider these variable stopping distances on wet roads according to tire tread depth: