How to Check Tire Tread Depth with a Penny

Here's a trick I've shown customers for 25 years, and it still works better than any gadget: you can check whether your tires are safe with nothing but a penny from your pocket. It takes about a minute, costs you one cent, and it could save you from driving on tires that have nothing left to give. Let me walk you through it.

The penny test, step by step

Grab a penny and do this on each tire:

1. Insert the penny into a tread groove with Lincoln's head pointing down, facing you.
2. Look at how much of his head the tread covers.
3. If the tread covers part of his head, you still have enough tread. If you can see the very top of his head, your tread is at or below 2/32" — it's time to replace the tire.
4. Repeat in several grooves across the width of the tire and at a few points around it.

That's the whole test. The reason it works: the distance from the edge of a penny to the top of Lincoln's head is right around 2/32 of an inch — the legal minimum tread depth in most states.

What 2/32" actually means

Tread depth is the height of the rubber ribs that grip the road. Brand-new tires usually start around 10/32" to 11/32". As you drive, that rubber wears down. Once it reaches 2/32", the tire is considered legally worn out — and for good reason. At that depth a tire can barely channel water out from under itself, so it loses grip in the rain and takes much longer to stop. The penny test is simply a pocket-sized way to find that 2/32" line without a gauge.

The quarter test for an earlier warning

The penny tells you when a tire is finished. If you'd rather know before you're down to the wire, use a quarter the same way: insert it with Washington's head down. If the tread reaches his head, you've got about 4/32" left. That's the point where wet-weather performance really starts to fall off, so it's a smart moment to start shopping rather than waiting for the hard 2/32" cutoff. Think of the quarter as your "start planning" signal and the penny as your "replace now" signal.

Check more than one spot — what uneven wear tells you

Don't just test one groove and call it a day. Check the inner edge, the center, and the outer edge of each tire. If one area is worn down to the penny line while the rest still has plenty of tread, that's not normal aging — it's a sign something else is going on. Worn edges often point to low tire pressure; a worn center can mean overinflation; and one-sided wear frequently traces back to alignment. If you're seeing that, it's worth reading up on why your alignment matters, because fixing the cause will protect your next set of tires too.

Tread depth isn't the only sign you need tires

The penny test is the fastest check, but tread depth is only part of the story. Also keep an eye out for cracks in the sidewall, bulges or blisters, vibration while driving, and the tire's age — rubber degrades over the years even on a tire that looks fine. And the best way to delay that 2/32" day in the first place is good habits: proper inflation, regular rotation, and not riding on a bad alignment. We cover all of them in our post on 5 habits that make your tires last.

When the penny tells you it's time, knowing your tire size makes replacing them painless — here's how to read your tire size straight off the sidewall.

Written by Gaby, founder of TIRE OX. After 25 years in the tire and auto industry, I started TIRE OX to sell tires the honest way — and to teach drivers how to make them last.