How to check tyre tread depth

Checking your tyre tread depth is a quick safety check that helps ensure your tyres provide adequate grip, especially in wet conditions.

What you’ll need

• A tyre tread depth gauge (recommended), or

• A 20p coin for a quick visual check

• Your car parked on level ground

Step 1: Know the UK legal minimum

In the UK, the legal minimum tread depth for cars is:

• 1.6 mm

• Across the central three-quarters of the tyre

• Around the entire circumference

Driving with tyres below this limit is illegal and unsafe.

Step 2: Inspect the tyre

Before measuring, look for:

• Uneven wear

• Cuts or cracks

• Bulges in the sidewall

• Objects embedded in the tread

If you notice any of these, have the tyre inspected even if the tread depth is legal.

Step 3: Measure the tread depth

Using a tread depth gauge:

1. Insert the probe into one of the main tread grooves.

2. Press the gauge firmly against the tyre.

3. Read the measurement.

4. Repeat at several points across the width of the tyre and around its circumference.

Measure all four tyres.

Step 4: Use the 20p coin test

If you don't have a tread depth gauge:

1. Insert a 20p coin into the main tread groove.

2. If the outer band of the coin is hidden, the tread is generally above the legal limit.

3. If the outer band is fully visible, the tread may be below the legal limit and should be checked with a tread depth gauge.

The 20p test is a useful guide but is not a substitute for an accurate measurement.

Step 5: Check the tread wear indicators

Most tyres have tread wear indicators built into the grooves.

• These are small raised bars across the tread.

• When the tread is level with these bars, the tyre has reached its wear limit and should be replaced.

Tips

• Check your tyre tread at least once a month.

• Measure the tread across the whole tyre—uneven wear can indicate alignment or suspension issues.

• Front tyres often wear faster on front-wheel-drive vehicles, while rear tyres may wear faster on rear-wheel-drive vehicles.

• Many experts recommend replacing tyres before they reach the legal minimum, especially if you regularly drive in wet weather, as braking and grip can reduce as tread depth decreases.

Safety notes

• Replace tyres immediately if they are below the legal tread depth.

• Check tyre pressures regularly, as incorrect pressures can cause uneven tread wear.

• If you notice uneven wear on one edge of the tyre, have your wheel alignment and suspension inspected.