Your tires’ tread is what grips the road and channels away water, so worn tread means longer stopping distances and a much higher risk of skidding or hydroplaning. The good news is you can check tread depth in a couple of minutes with a coin you already have in your pocket. Here’s exactly how to check tire tread, step by step — the penny test, the quarter test, the built-in wear bars — plus what the results mean and the mistakes to avoid.
- Penny test: insert a penny with Lincoln’s head pointing down. If you can see the top of his head, tread is at or below 2/32″ — replace the tire now.
- Quarter test: same idea with Washington’s head measures to about 4/32″ — a safer point to start shopping for new tires, especially for wet weather.
- Every tire has molded tread wear bars at 2/32″; when the tread is flush with them, the tire is legally worn out.
- 2/32″ (1.6 mm) is the legal minimum in most US states; check several spots on each tire and look for uneven wear.
- Check tread monthly and before long trips — it only takes a minute and the coin is free.
The short answer: Push a penny into the tread groove with Lincoln’s head upside down. If part of his head is always covered, you have more than 2/32″ of tread and you’re legal. If the top of his head is fully visible, the tire is worn to the legal limit and should be replaced.
How to check tire tread: step by step
Park on level ground with the engine off and the parking brake set before you kneel down beside the tires.
- Park safely. Stop on flat, level ground, turn off the engine, and set the parking brake so the car can’t move while you check.
- Grab a penny. Hold it so Lincoln’s head points down into the groove and you’re looking at the front of the coin.
- Insert it into the tread. Push the penny into one of the main grooves until it stops.
- Read the result. If part of Lincoln’s head is always covered by tread, you have more than 2/32″ left. If you can see the very top of his head, the tread is at or below 2/32″ — time to replace.
- Repeat with a quarter. For an earlier warning, do the same with a quarter: if you can see the top of Washington’s head, you’re down to about 4/32″ and should start planning for new tires.
- Check multiple spots. Test the outer edge, center, and inner edge of each tire, and check all four tires. Differences point to uneven wear.
- Look at the wear bars. Find the small raised rubber bars running across the grooves; if the tread is level with them, the tire is worn out.
- 6/32″ and above: healthy tread; good grip in rain and (for all-season tires) light snow.
- 4/32″ (quarter test fails): start shopping; wet-weather braking and hydroplaning resistance are noticeably reduced.
- 2/32″ (penny test fails / flush with wear bars): legally worn out in most states — replace immediately.
- Winter/snow tires: many experts recommend replacing around 5–6/32″ because snow traction drops off sooner.
- Uneven wear: edges worn faster than the center can mean under-inflation; center worn faster can mean over-inflation; one-sided wear suggests alignment issues.
What the results mean
If the penny test passes (Lincoln’s head is partly covered everywhere you check), your tires still have usable tread, though the quarter test gives you a safer heads-up: failing the quarter test at about 4/32″ is a sign to start budgeting for replacements, because stopping distances on wet roads grow dramatically between 4/32″ and 2/32″. If the penny test fails or the tread is flush with the wear bars, the tire is at the legal minimum of 2/32″ and should be replaced now — don’t wait. Pay just as much attention to how the tire is wearing: even wear across the tread is normal, but wear concentrated on the edges, the center, or one side points to inflation or alignment problems you should have checked. Also look for cracks, bulges, or embedded objects, which call for a professional inspection regardless of tread depth.
Common mistakes to avoid
- Checking only one spot — tires wear unevenly, so test the inner, center, and outer grooves and all four tires.
- Trusting the penny alone — it only confirms the 2/32″ legal minimum. By the time it fails, grip is already poor; the quarter test warns you earlier.
- Ignoring the spare — your spare ages and loses pressure too; check it before you actually need it.
- Reading the number on the tire sidewall — that’s the tire size and spec, not your tread depth. Use the coin or a gauge.
- Overlooking wear patterns — fixing the underlying inflation or alignment issue makes your next set of tires last far longer.
How often should I check my tire tread?
Check tread depth and tire condition about once a month, and always before a long road trip or the start of a rainy or snowy season. Tires also lose pressure over time, so it’s a good habit to check tread and inflation together. If you notice longer stopping distances, more road noise, or the car pulling to one side, check sooner.
How to check tire tread FAQ
What is the legal minimum tire tread depth?
In most US states the legal minimum is 2/32″ (about 1.6 mm). A few states differ — California, for example, allows as low as 1/32″ on some tires — but 2/32″ is the widely used safety threshold the penny test measures.
Is the penny test or the quarter test better?
Use both. The penny test shows whether you’ve hit the 2/32″ legal limit. The quarter test flags about 4/32″, giving you time to replace tires before wet-road grip gets dangerous.
What are tread wear bars?
They’re small rubber bars molded across the bottom of the grooves at 2/32″. When the surrounding tread wears down level with them, the tire is at the legal minimum and should be replaced.
Can I just replace one worn tire?
Sometimes, but it’s best to replace tires in pairs (or all four, especially on all-wheel-drive vehicles) so grip stays balanced. A single new tire paired with worn ones can affect handling.
Does tread depth affect stopping distance?
Yes, significantly in the wet. Shallow tread can’t clear water, so braking distances lengthen and hydroplaning becomes more likely well before you reach the 2/32″ limit.
How accurate is the penny test?
It’s a reliable quick check for the legal minimum but only a rough estimate. For precise readings use an inexpensive digital or probe-style tread depth gauge and measure several points.
When should I replace winter tires?
Earlier than summer or all-season tires — many experts suggest replacing them around 5–6/32″ because snow and slush traction falls off well before 2/32″.
Sources & last update: Based on standard manufacturer guidance and common DIY practice; always follow your owner’s manual and local regulations. Last reviewed and updated November 2026. Specific intervals, legal limits, and specs vary by vehicle and by state.