Tire tread depth guide
What is the minimum tire tread depth?
The legal minimum tread depth in most countries is 1.6 mm (2/32"). Most safety organisations recommend replacing tyres at 3 mm (4/32") because stopping distances increase sharply below that threshold. A new tyre has approximately 8 mm (10/32") of tread. The penny test (insert a 1p / US 1¢ coin headfirst into the tread groove — if the full head is visible, the tread is below 2/32") provides a quick on-car check.
- The legal minimum tread depth in most countries is 1.6 mm (2/32").
- Most safety organisations recommend replacing tyres at 3 mm (4/32") because stopping distances increase sharply below that threshold.
- A new tyre has approximately 8 mm (10/32") of tread.
FAQ
- What is the minimum tire tread depth?
- The legal minimum tread depth in most countries is 1.6 mm (2/32"). Most safety organisations recommend replacing tyres at 3 mm (4/32") because stopping distances increase sharply below that threshold. A new tyre has approximately 8 mm (10/32") of tread. The penny test (insert a 1p / US 1¢ coin headfirst into the tread groove — if the full head is visible, the tread is below 2/32") provides a quick on-car check.
- What should I verify before using this information?
- Use TireFitLab values as a sizing reference, then verify the vehicle handbook, tire placard, rim compatibility, load rating, and physical clearance before fitting.
Tread depth action chart
| Depth (mm) | Depth (32nds)" | Condition | Action |
|---|---|---|---|
| 8–9 mm | 10–11/32" | New tyre | Normal use. Check monthly. |
| 5–7 mm | 6–9/32" | Good | Normal use. Check every 3 months. |
| 4 mm | 5/32" | Serviceable | Consider replacement soon, especially in wet/winter conditions. |
| 3 mm | 4/32" | Safety threshold | Replace. Wet braking degrades sharply below this point. |
| 1.6 mm | 2/32" | Legal minimum | Replace immediately. Illegal in EU, UK, US (2/32" for cars). |
| < 1.6 mm | < 2/32" | Unsafe / illegal | Must be replaced. Significantly increases risk of aquaplaning. |
The penny test (US)
Insert a US penny (Lincoln head) into the tread groove, head down. If you can see Lincoln’s entire head, the tread is at or below 2/32" (1.6 mm) — replace immediately. If part of the head is obscured, the tread is still above the minimum.
The quarter test (a 25¢ coin) gives the 4/32" (3 mm) warning line: if Washington’s head is fully visible, tread is below the safety recommendation.
UK / EU coin test
For UK/EU markets, use a 20p coin: insert it into the tread — if the outer band of the coin is visible, the tread is at or below 1.6 mm and the tyre is illegal. This equates to the same 2/32" threshold as the US penny test.
How to measure accurately
Use a tread depth gauge (a small, inexpensive tool that slides into the groove). Measure in at least 3 positions across the tyre width and 3 positions around the circumference. The minimum reading is your effective tread depth.
- Centre groove — typically wears fastest
- Inner shoulder groove — check for misalignment wear (one-sided)
- Outer shoulder groove — check for overinflation wear (edge wear)
Winter tyres: deeper minimum
Winter/snow tyres are classified as winter tyres down to 4 mm of tread (EU best practice). Below 4 mm, cold-weather grip degrades significantly. Replace winter tyres at 4 mm rather than waiting for the 1.6 mm legal minimum.
More tools
- Tire age guide
- Tire type guide
- How to read a tire size
- Tire size calculator
- Tire & wheel reference guides
Seasonal check
Planning a long summer drive?
Use the budget and running-cost tools before a trip, especially if the current tyres are worn or the replacement size changes diameter.
What changed
- Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.