New tires start around 10-11/32 inch (8-9mm) of tread. The UK legal minimum is 1.6mm across the central three-quarters of the tread, checked at every MOT. In the US, legal minimums are set by state and mostly sit at 2/32 inch (1.6mm), but safety groups including many state DOTs recommend replacing at 4/32 inch (3.2mm), since wet-weather stopping distances get measurably worse below that. India has no single nationwide legal minimum tread depth number under the Central Motor Vehicle Rules, but CMVR still requires tyres to be roadworthy and not "bald" — traffic police can flag visibly worn tyres. Use the simple coin test to check.
At a glance
| Region | Legal minimum | Recommended replacement |
|---|---|---|
| UK | 1.6mm across central 3/4 of tread (MOT-checked) | 3mm in wet-heavy regions per TyreSafe |
| US | 2/32 in (1.6mm) in most states, varies by state | 4/32 in (3.2mm) per many state DOTs and AAA |
| India | No single fixed national legal figure; must not be visibly bald | 3-4mm as tread wears toward wear bars |
| New tire tread depth | 10-11/32 in (8-9mm) typical | — |
Legal minimum vs. safe minimum
These are two different numbers and mixing them up is a common mistake. The legal minimum is the absolute floor before you risk a fine, points, or an MOT/inspection failure. The safe minimum is higher, because wet-weather braking distance and hydroplaning resistance degrade measurably as tread wears down — independent testing consistently shows a tire at 2/32 inch stops significantly worse in the wet than the same tire at 4/32 inch or above. Treating the legal minimum as your target is treating the worst-case legal line as a maintenance goal, which isn't the same as driving safely.
How to check tread depth at home
- Coin test (quick check): insert a coin into the tread groove upside down. In the US, if you can see all of Lincoln's head on a penny, tread is at or below 2/32 inch — replace now. In the UK, a 20p coin's outer band disappearing into the groove roughly indicates the 1.6mm legal limit.
- Tread depth gauge (accurate check): insert the small pin into a groove and read the depth directly in 32nds of an inch or millimeters.
- Check at least three points across each tire — inner edge, center, and outer edge — since uneven wear can mean one area is fine while another is already low.
- Check the built-in tread wear indicator bars molded into the tire's grooves — when tread is flush with these raised bars, the tire is at its wear limit.
Uneven wear across the tread — more worn on one edge, or wear only in the center — often points to an alignment, inflation, or suspension issue, not just normal aging. Fix the root cause or the new tires will wear the same way.
Why wet-weather stopping distance matters most
Tread grooves exist to channel water away from the contact patch — as they wear shallow, they can't move water fast enough at speed, and the tire starts to ride partly on a film of water (hydroplaning) rather than the road surface. This is why the practical safety gap between the legal minimum and a recommended replacement point is almost entirely about wet roads; dry-road grip degrades far less with tread wear.
How long does a set of tires last?
Most passenger car tires are rated for roughly 40,000-70,000 miles (64,000-112,000 km), but real-world life depends heavily on alignment, inflation habits, rotation schedule, and driving style — aggressive acceleration and hard cornering can cut that number substantially. Checking tread depth monthly alongside pressure checks catches wear trends early enough to budget for replacement rather than being surprised by it.
Regional testing notes
The UK's MOT test physically measures tread depth on all tires including the spare if fitted for use, and driving on an illegal tire carries a fine and penalty points per tire, not per vehicle. The US has no federal tread depth law — it's set state by state, so the exact legal number and any inspection requirement varies depending on where you live. India's CMVR framework focuses on general roadworthiness rather than a single published millimeter figure, so a visibly smooth or bald tyre is the practical enforcement trigger rather than a specific depth number.
Frequently asked questions
What is the legal tire tread depth limit?
How do I check tire tread depth without a gauge?
At what tread depth should I actually replace tires?
Do all four tires need the same tread depth?
How fast does tire tread wear down?
Sources & further reading
Figures, prices and policy details were current at the last-updated date above. Automotive pricing, incentives and regulations change frequently — verify time-sensitive details with the linked primary sources. Read our editorial policy and fact-checking standards.
