Where does your tread stand?
Estimate remaining life
Rough projection assuming even wear at your historic rate.
The coin tests, and why 2/32 is not enough
The legal minimum in the US and much of the world is 2/32″ (1.6 mm), marked by the moulded wear bars in the grooves. But wet braking and hydroplaning resistance fall off a cliff well before that. Testing consistently shows meaningful loss of wet performance by 4/32″ (3.2 mm), which is why that is the widely recommended replacement point for wet climates.
| Test | What it checks | Reading |
|---|---|---|
| Penny (Lincoln's head) | The legal 2/32″ limit | Insert head-down. If you see all of Lincoln's head, you are at or below 2/32″ — replace now. |
| Quarter (Washington's head) | The safer 4/32″ threshold | Insert head-down. If the top of Washington's head shows, you are at or below 4/32″ — start shopping. |
| Penny (Lincoln, other way) | The "Memorial" check ~6/32″ | If the top of the Lincoln Memorial shows, you are below about 6/32″. |
| Built-in wear bars | The 2/32″ limit | When the bars sit flush with the tread surface, the tire is legally worn out. |
Replace at these depths
- Summer / dry: 2–3/32″ (1.6–2.4 mm) — the legal floor.
- Wet climates: 4/32″ (3.2 mm) — hydroplaning resistance is already degrading.
- Winter tires: 5–6/32″ (4–5 mm) — snow traction needs groove volume that thin tread cannot provide. See winter tire science.
Reading uneven wear
Tread depth is not just a countdown — the pattern of wear diagnoses the car. Measure across the tread, not just in the middle:
| Wear pattern | Likely cause |
|---|---|
| Both edges worn, centre fine | Chronic underinflation |
| Centre worn, edges fine | Chronic overinflation |
| One edge only | Camber or alignment out of spec |
| Feathered / saw-tooth edges | Toe misalignment |
| Cupping / scalloped patches | Worn shocks or unbalanced wheels |
Correct inflation prevents the two most common patterns — check yours with the pressure calculator. And remember that depth is only half the replace-or-keep decision: a tire with good tread but a very old DOT date code should still be retired.