Tire Tread Depth Calculator
Convert tire tread depth between 32nds of an inch and millimeters, estimate remaining tread life from your wear rate, and check if your tires meet legal and safety thresholds for wet and winter driving.
Tire Tread Depth Calculator
Estimate remaining tread life and miles until replacement.
How It Works
New passenger tires start with 10/32″ (8 mm) of tread. The US legal minimum is 2/32″ (1.6 mm), but wet-traction loss begins at 4/32″ (3.2 mm) and most tire safety organizations now recommend replacing at 4/32″ for rain and 5/32″ for snow.
How to Use This Calculator
- Measure tread depth at three points across the tire — outer edge, center, inner edge.
- Use the lowest reading as your current depth — uneven wear indicates alignment or pressure issues.
- Enter the depth in 32nds or mm (the calculator accepts either).
- Enter miles driven since the tires were new (or since last measurement).
- Click Calculate for remaining life percent and estimated miles until 4/32″.
Worked Example
Reference Table
The “penny test” works: insert a penny into the tread groove with Lincoln’s head pointing down. If you can see the top of his head, you are at or below 2/32″.
| Depth (32nds) | Depth (mm) | Status |
|---|---|---|
| 10/32″ | 8.0 mm | New passenger tire |
| 9/32″ | 7.1 mm | Like-new |
| 7/32″ | 5.6 mm | Healthy — good for all conditions |
| 5/32″ | 4.0 mm | Replace soon for winter driving |
| 4/32″ | 3.2 mm | Replace for rain — wet braking is degraded |
| 3/32″ | 2.4 mm | Approaching legal minimum |
| 2/32″ | 1.6 mm | US/EU legal minimum — replace immediately |
| 1/32″ | 0.8 mm | Illegal in most jurisdictions |
Frequently Asked Questions
What is the legal tire tread minimum?
In the US and EU it is 2/32″ (1.6 mm). In Germany passenger cars must have at least 1.6 mm but winter tires need 4 mm. In the UK it is 1.6 mm across the central three-quarters of the tread.
How do I measure tire tread without a gauge?
Insert a penny into the tread groove with Lincoln’s head pointing down. If the top of his head is visible, your tread is at or below 2/32″ and the tire must be replaced. Use a quarter (Washington’s head) for the 4/32″ wet threshold.
How long do tires last in miles?
Most all-season tires are rated for 50 000–80 000 miles, performance tires 25 000–45 000 miles, off-road tires 30 000–60 000 miles. The treadwear rating on the sidewall is a relative number — a 600-rated tire lasts ~2× as long as a 300-rated one.
Should all four tires have the same tread depth?
For AWD/4WD vehicles, yes — many manufacturers require all four tires within 2/32″ of each other to avoid driveline damage. For FWD/RWD, differences up to 3/32″ are acceptable.
When should winter tires be replaced?
Winter tires lose snow traction below 5/32″ (4 mm) — well above the legal limit. Replace winter tires once they reach 5/32″ even if they still look good.
