Tread depth is measured in 32nds of an inch in the US. New tires typically start at 10/32" or 11/32" (about 8mm). The legal minimum is 2/32". But the legally safe minimum and the actually safe minimum are not the same number.
Tread depth reference chart
10/32"–11/32" — New tire tread depth for most passenger tires. Full grip, full wet weather performance, full lifespan ahead.
8/32"–9/32" — Good condition. Most of the tire's life ahead. Wet and snow traction still strong.
6/32" — Adequate for wet road performance. Many tire experts consider this the point to start budgeting for replacement in the next year.
4/32" — Meaningfully degraded wet traction. Studies show stopping distances in rain increase noticeably below 4/32". Plan for imminent replacement.
3/32" — Significantly reduced wet grip. Hydroplaning risk increases substantially. Replace soon.
2/32" — Legal minimum in most US states including Georgia. The penny test level. The tire is at end-of-life — replace immediately. Wet weather stopping distances can be 40–50% longer than a new tire.
How to measure tread depth
Tread depth gauge (most accurate): available at auto parts stores for $5–15. Insert the probe into the tread groove, push the barrel down to the tread surface, read the measurement. Check multiple points across the tread width and in several locations around the circumference.
Quarter test: insert a quarter into the tread groove with Washington's head pointing in. If you can see the top of his head, the tread is at 4/32" or less — time to plan replacement.
Penny test: insert a penny with Lincoln's head pointing in. If you can see the top of his head, the tread is at 2/32" or less — the tire is at the legal limit and needs immediate replacement.
Tread wear indicators: built into the tire tread grooves at 2/32" depth. Small raised bars appear at the bottom of the grooves when the tire reaches the legal limit.
Where to measure
Measure at multiple points across the tread width (center and both outer edges) — uneven wear from alignment or inflation issues shows up as different readings across the tire.
Measure in multiple locations around the tire circumference — cupped or scalloped wear shows up as inconsistent readings at the same width position.
The shallowest reading anywhere on the tire determines its safe tread life — not the average.
When to replace vs. when to wait
6/32" or below with rain driving: budget for replacement within the next few months. The wet-weather safety degradation is real.
4/32" or below: replace soon — within the next few weeks. Do not wait for a rain storm to discover the handling difference.
2/32": replace immediately. You are at the legal minimum and meaningfully unsafe in wet conditions.
New tires at 6/32" due to uneven wear (alignment, balance, inflation issues): replace them and fix the underlying issue — or the same thing will happen to the next set.
Frequently asked
How often should I check tire tread depth?
At every oil change (every 5,000–7,500 miles) is the most practical cadence — most shops will check it for free. Also check when you rotate tires and before any long road trip.
Is 4/32" enough tread to pass inspection in Georgia?
Georgia's legal minimum is 2/32" — any tread above that passes inspection. But 4/32" is below what most safety organizations recommend for wet-road safety. Legally compliant and actually safe are different thresholds.
Do all tires start at the same tread depth?
No. Most passenger tires start at 10/32" or 11/32". Some performance tires start at 9/32" — trading tread life for stickier compound. Winter tires often start at 11/32"–12/32" for snow performance. Truck and A/T tires typically start at 12/32"–15/32".
What if only one tire is worn out?
Replace the worn tire. On most vehicles, replacing a single tire is fine — match the brand and model of the other tires on the same axle if possible. On AWD vehicles, check tread-depth differences between all four tires and consult your manual about matching requirements.
Keep reading
Last updated 2026-06-27. General guidance only — confirm specifics with a local shop for your exact vehicle.