What Makes Your Tyres Illegal? A Guide to Staying Roadworthy

Tyres are one of the most critical components of your vehicle, directly impacting safety, handling, and fuel efficiency. Driving on illegal tyres isn’t just dangerous—it can result in hefty fines, penalty points on your license, or even accidents. But what exactly makes a tyre illegal? Let’s break it down.

 1. Tread Depth Below the Legal Limit

 The UK legal minimum tread depth for cars, vans, and light trailers is 1.6mm across the central three-quarters of the tyre and around the entire circumference.

Why is tread depth important?

• Grip: Tread channels water away from the tyre, preventing aquaplaning.

• Braking: Reduced tread depth means longer stopping distances.

 How to check your tread depth:

• Use a tread depth gauge or the edge of a 20p coin. Insert the coin into the tread grooves—if the outer rim is visible, your tyre may be below the legal limit.

 Penalty for illegal tread depth:

Driving with tyres below the legal limit can result in a £2,500 fine per tyre and three penalty points.

 2. Visible Tyre Damage

 Tyres with cuts, bulges, or exposed cords are illegal and unsafe.

Common causes of damage:

• Hitting potholes or curbs.

• Driving over sharp objects.

• Over- or under-inflation.

Why is damage dangerous?

A bulge or tear compromises the tyre’s structural integrity, increasing the risk of a blowout.

Check for:

• Cuts or tears longer than 25mm or 10% of the tyre’s section width.

• Bulges caused by internal damage.

• Exposed cords or steel reinforcement.

 3. Incorrect Tyre Size or Type

 All tyres must meet your vehicle manufacturer’s specifications.

Examples of non-compliance:

• Mismatched tyres on the same axle.

• Tyres not rated for your vehicle’s load or speed.

 How to ensure compliance:

Check your vehicle handbook for the recommended tyre size, load index, and speed rating.

 4. Excessive Tyre Wear or Age

 Even if the tread depth is legal, tyres that are excessively worn or aged can become unsafe.

How to spot ageing tyres:

• Cracks in the rubber, especially on the sidewalls.

• Hardening of the rubber, reducing grip.

Tip: Replace tyres that are more than six years old, even if they’re not worn out.

 5. Incorrect Tyre Pressure

 While not directly illegal, under- or over-inflated tyres can lead to uneven wear, reducing the tyre’s lifespan and performance. This may result in MOT failure or increased risk of accidents.

How to check tyre pressure:

• Use a pressure gauge at home or visit a local petrol station.

• Refer to the vehicle handbook for recommended pressures (adjusted for load if necessary).

 Stay Safe and Legal with Our Expert Tyre Services

Illegal tyres put you, your passengers, and other road users at risk. At our garage, we offer:

• Free tyre safety checks.

• Replacement tyres from trusted brands.

• Wheel alignment and balancing to extend tyre life.

If you’re unsure about your tyres, don’t take the risk—book a tyre check with us today. Together, we’ll keep you safe and roadworthy.