Tyre Tread Depth: The Legal Limit and Why It Matters

Your tyre's tread depth is critical to road safety. The grooves in your tyres channel water away from the contact patch between the rubber and the road — without sufficient depth, your car is significantly more prone to aquaplaning on wet roads.

The Legal Minimum

In the UK, the legal minimum tread depth for cars and light vans is 1.6mm across the central three-quarters of the tyre, around the entire circumference. Driving with tyres below this limit carries a fine of up to £2,500 per tyre and three penalty points on your licence.

Why 3mm Is the Recommended Change Point

Safety experts and tyre manufacturers recommend replacing tyres when the tread reaches 3mm — not 1.6mm. Testing shows that stopping distances in the wet increase dramatically below 3mm. The difference in wet stopping distance between a tyre with 3mm of tread and one at the 1.6mm legal limit can be significant, often over 8 metres at 50 mph.

How to Check Your Tread Depth

• Use a tread depth gauge — available inexpensively from any motor factors
• Use a 20p coin — insert it into the main grooves: if you can see the outer band of the coin, the tread is below 3mm and the tyre should be changed soon
• Check the tread wear indicators moulded into the tyre's grooves — when the tread wears level with these, the tyre is at the legal minimum

Uneven Tyre Wear

Tyres can wear unevenly across the width. Check tread depth at the inner edge, centre, and outer edge of each tyre. Uneven wear — worn on one side, or excessively worn in the centre or on both edges — indicates incorrect tyre pressure, wheel alignment issues, or suspension wear that should be addressed.

PKA Automotive checks tyre tread depth as part of every service and free vehicle health check. If your tyres need replacing, we can source and fit the correct tyres for your vehicle at competitive prices.