🛞 Tire Tread Wear Calculator

Enter your new tire's tread depth, current tread depth, and distance driven since new — this calculator computes total wear and wear rate per 1,000 km/mi, then estimates the distance remaining until the legal wear limit (1.6mm) and whether it's time to replace.

Results

Verdict

—

Total Wear

— mm

Wear Rate

— mm / 1,000 km

Wear % of Usable Depth

— %

Estimated Distance to Legal Limit

— km

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GUIDE

Learn more

How Tread Wear Is Measured & the Legal Limit

Tread depth is measured by inserting a tread-depth gauge into a groove and reading it in mm or 32nds of an inch. For accuracy, measure several grooves (outer, center, inner) and use the most-worn reading.

The legal minimum in Korea and the EU is 1.6mm; in the US it's 2/32" (about 1.59mm) — essentially the same standard. But the legal limit is just the "illegal below this" floor, not a safe replacement point. Wet-braking distance starts degrading sharply once tread drops to about 3mm (roughly 4/32"), so replacing before you hit the legal limit is the safer call.

Worked Example

New tread depth 8mm, current depth 4mm, 40,000km driven since new:

Total wear = 8 − 4 = 4mm
Wear rate = 4mm ÷ 40,000km × 1,000 = 0.1mm per 1,000km
Margin to legal limit (1.6mm) = 4 − 1.6 = 2.4mm
Estimated remaining distance = 2.4 ÷ 0.1 × 1,000 ≈ 24,000km

At this wear rate, the tire would reach the legal limit roughly 24,000km from now.

Caveats — Wear Isn't Perfectly Linear

This calculator assumes your average wear rate so far continues unchanged, which is a linear estimate. In practice, wear can accelerate with tire age (rubber hardening), misalignment, incorrect tire pressure, and aggressive driving (hard acceleration/braking) — so actual remaining life may be shorter than the estimate.

For a more reliable read, measure several grooves with an actual tread-depth gauge, and if you notice uneven wear across the tire, get your alignment and tire pressure checked first.

Frequently asked questions

Why is 1.6mm the legal tread limit?

Most jurisdictions, including Korea and the EU, set 1.6mm as the minimum legal tread depth. Below that, the grooves that channel water away nearly disappear, sharply raising the risk of hydroplaning on wet roads, and the vehicle can fail inspection or be cited. The US limit of 2/32" is effectively the same standard.

Why replace at 3mm if the legal limit is 1.6mm?

As tread gets shallower, the groove volume available to channel water shrinks, and wet-braking distance increases non-linearly. Independent tire tests consistently show a noticeable jump in stopping distance around 3mm (roughly 4/32"), so replacing at that point — rather than riding it down to the legal minimum — preserves your safety margin.

How do I check tread depth without a gauge?

A coin test is a quick, rough check (not a precise measurement). For example, insert a penny into a groove with Lincoln's head down — if you can see the top of his head, tread is getting low. It's useful for a fast sanity check, but for replacement decisions or this calculator's inputs, measure with an actual tread-depth gauge in mm or 32nds.

Does the wear rate apply evenly across the whole tire?

No. This calculator only computes the average wear rate at the single point you measured (ideally the most-worn groove). Wear can differ between the inner, center, and outer tread; if you see uneven wear, it may signal an alignment or pressure issue worth having checked.