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Calculators & Converters
Automotive

Tire Life Calculator

Estimate how many more miles your tires will last based on original tread depth, current tread depth, and miles already driven.

New tires are commonly ~10/32in deep

2/32in (~1.6mm) is the commonly cited US legal minimum; the UK/EU legal minimum is also 1.6mm (about 2/32in), so 2/32in is a reasonable default either way.

What Does This Tire Life Calculator Do?

This calculator estimates how many more miles your tires will last based on how much tread has worn away so far. Enter your original tread depth, current tread depth, miles driven, and the legal minimum tread depth for your area, and it projects your remaining tire life.

The Tire Wear Formula

Wear Rate = (Original Tread - Current Tread) / Miles Driven
Remaining Miles = (Current Tread - Legal Minimum) / Wear Rate

Worked Example

New tires at 10/32 in, now at 6/32 in after 20,000 miles, with a legal minimum of 2/32 in:

  • Worn so far: 10 - 6 = 4/32 in
  • Wear rate: 4 / 20,000 = 0.0002 per mile
  • Remaining tread: 6 - 2 = 4/32 in
  • Remaining miles: 4 / 0.0002 = 20,000 more miles
  • Total estimated tire life: 20,000 + 20,000 = 40,000 miles

Getting an Accurate Reading

For the most accurate estimate, measure tread depth at several points around each tire (wear isn't always even) and use a proper tread depth gauge rather than eyeballing it. This calculator gives a straight-line projection based on your wear so far, which is a reasonable approximation for most driving conditions.

See also the tire size calculator to compare tire diameters when shopping for a replacement.

Frequently Asked Questions

How do I measure tire tread depth?
Use a tread depth gauge, or the 'penny test' (insert a penny with Lincoln's head down into the tread groove — if you can see all of his head, tread is worn below about 2/32 inch). Tread depth is measured in 32nds of an inch in the US.
What is the legal minimum tire tread depth?
In the US, 2/32 inch (about 1.6mm) is the commonly cited legal minimum in most states. The UK and EU legal minimum is also 1.6mm, which is roughly equivalent to 2/32 inch, though some safety experts recommend replacing tires earlier, around 4/32 inch, for better wet-weather performance.
How is remaining tire life calculated?
First, calculate your wear rate: (Original Tread - Current Tread) / Miles Driven. Then divide the remaining usable tread (Current Tread - Legal Minimum) by that wear rate to estimate remaining miles.
How deep is a new tire's tread?
Most new passenger car tires start with about 10/32 inch to 11/32 inch of tread depth, though this varies by tire model and manufacturer.
Why might my tire wear estimate be inaccurate?
Tire wear isn't always linear — driving habits, alignment issues, tire rotation frequency, road conditions, and climate all affect wear rate over time, so this is an estimate based on your wear so far, not a guarantee.
Should I replace tires before they hit the legal minimum?
Many safety experts and tire manufacturers recommend replacing tires once tread reaches about 4/32 inch, especially for wet-weather driving, since stopping distance and hydroplaning resistance both degrade noticeably as tread wears down, even before the legal minimum.
Does tire rotation affect this estimate?
Yes — regular tire rotation helps tires wear more evenly, which can extend overall tire life. This calculator assumes your current wear rate (based on your inputs) will continue at the same pace going forward.

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How this is calculated: This tool uses standard, well-established formulas for automotive calculations. Results are estimates for informational and planning purposes — always double-check figures for anything with real-world consequences (e.g. ordering materials or submitting grades).