Ensuring that your tire’s tread depth is both legal and safe is an essential part of making sure that your car or vehicle is safe to drive. Thankfully you don’t need any expensive equipment to do this, and can in fact simply use a coin to check depth. Here’s my quick guide on how you can do it including some photos. But first, just a recap on the law regarding tire tread depths.
Most states have laws that state a tire is legally no longer allowed once the tire tread depth has worn down and degraded to 2/32” of depth remaining. Some tires sold in the United States have small indicators set into the tread design which are visual indicators to show when your tires have worn down to un-safe levels. Look for the “wear bars” which are molded over the tread pattern from one side to the other. If you don’t see the bars then it’s time to change your tires.
Alternatively, you might not have tires with these safety features so can instead use the coin test. Here’s a quick overview of how you do it.
Insert a penny into some of the tire tread grooves over random parts of the tire. If you notice that part of Lincoln’s head is covered by the tread then this is ok as your tire will have in excess of 2/32” remaining tread rubber and is legal to drive with (see photos below).
Image 1: If you use a quarter you can do the same test to check your tires. If any part of the head of President Washington’s head is covered then that means you have even more tread left with 4/32” remaining.
Image 2: Finally you can check again with a penny. Doing the same test, if the top of the Lincoln Memorial is covered by the thread then this is an indication of your tire having 6/32” of tread depth left.
Image 3: Place a penny into several tread grooves across the tire. If the top of the Lincoln Memorial is always covered by the tread, you have more than 6/32″ of tread depth remaining.
There is an additional tire check test that you can do as well. Once you’ve checked tread depth using the method outlined above then do the coin test 15 inches apart. If the part of the hidden coin changes then this is a great indication that your tire is uneven – which can be dangerous even with tires that are legally correct.