Tyres MOT Check: What Will Make You Fail?

Tyres are one of the most scrutinised areas during your MOT – and for good reason.

They’re the only point of contact between your car and the road, and if something’s not right, it can significantly compromise your safety.

But can poor tyre condition really lead to an MOT failure? Yes – as reported through our MOT test results report, tyre-related issues are among the top three reasons UK vehicles fail their MOT each year.

In this guide, we’ll walk through what’s inspected during an MOT when it comes to tyres, the most common reasons for failure, and what you can do to avoid it.
 

What Do MOT Testers Check on Your Tyres?

During your MOT, a certified inspector performs a thorough visual and functional inspection of your vehicle’s tyres.
Here's what they’ll be looking for:
 

Tread Depth

The legal minimum tread depth for most cars is 1.6mm across the central three-quarters of the tyre, measured around the full circumference. If even one tyre falls below this, it’s classed as a dangerous defect and will result in an automatic fail.
 

Tyre Condition

The sidewalls are checked for cuts, bulges, or tears. Any visible structural damage – such as a bulge indicating internal separation – is a red flag and likely to result in failure.
 

Tyre Type, Size & Structure

MOT testers ensure all tyres are of the correct size and load rating for the vehicle. Additionally, tyres on the same axle must be of compatible structure – for example, two radial-ply tyres should not be mixed with cross-ply tyres on the same axle.
 

Pressure & TPMS (Tyre Pressure Monitoring System)

On vehicles registered after 1 January 2012, your TPMS must be working properly. A faulty TPMS warning light showing during the test is marked as a major defect. Tyres that are obviously under-inflated may also trigger a minor defect advisory.
 

Common Tyre Issues That Lead to MOT Failure

If your tyres have any of the following defects at the time of testing, your car is likely to fail its MOT:
 

1. Tread Below the Legal Limit

This is one of the most common causes of tyre-related MOT failures. Insufficient tread compromises grip, especially in wet weather. Testers use a gauge to measure tread depth, and anything under 1.6mm is a dangerous defect.

Quick tip: Use the 20p coin test. Insert the coin into the tread groove – if you can see the outer rim, your tread may be too low.

2. Cuts, Bulges or Cracks

Tyres with cuts deep enough to expose cords, or bulges caused by internal damage, will result in an immediate fail. These are not just MOT concerns – they’re serious safety risks.
 

3. Wrong Tyres for the Vehicle

If the tyres don’t meet your vehicle’s required size, speed rating or load index, that’s a major defect. This includes mixing mismatched structures on the same axle (e.g. radial with cross-ply).
 

4. Incorrectly Fitted Tyres

Tyres mounted against the directional arrow or with asymmetric sidewalls fitted incorrectly (‘outside’ on the inside) won’t necessarily result in a fail, but the tester may advise you to correct it.
 

5. TPMS Malfunction

If your TPMS light is on due to a malfunction, and your vehicle was registered from 2012 onwards, you’ll fail your MOT with a major defect. A low-pressure warning alone may result in an advisory, but not a fail.
 

How to Avoid an MOT Fail Because of Your Tyres

Avoiding a tyre-related MOT failure comes down to regular checks, maintenance, and knowing what to look out for.
 

Do a Pre-MOT Tyre Check

Before your test, inspect all four tyres (and the spare tyre, if fitted) for:

• Tread depth: Use a 20p coin or a tread depth gauge.
• Sidewall damage: Look for bulges, tears, cracks or foreign objects.
• Even wear: Excess wear on one edge may indicate wheel misalignment.
• Inflation: Check tyre pressures against the manufacturer’s recommendations – found in the car manual or on the fuel flap.
• Age: While not all vehicles are tested for tyre age, tyres over 10 years old on certain vehicles (like minibuses) can result in a fail.

Choose Quality Replacements

If your tyres are worn or damaged, replace them before the test. Cheap part-worn tyres can be tempting, but they have poor wear history and may not meet legal standards, being a risk to not just you, but others.

Stick to reputable, preferably premium tyre brands for the highest quality tyre models.
 

Keep Your TPMS in Working Order

If your TPMS warning light is on, it may just need a reset – especially after a tyre change. If not, it might require sensor or battery replacement. Ask your garage to inspect it before the MOT.
 

Advisory Notes vs MOT Fails: Know the Difference

Tyres don’t always lead to an MOT fail. Sometimes, they’ll trigger an advisory, meaning they’re close to the limit or showing signs of concern but not yet illegal.
Common tyre advisories include:

• Tread depth approaching 1.6mm
• Minor cracks or perishing
• Uneven wear patterns
• Surface cuts that don’t expose cords

While these may not fail the MOT test, they signal future issues – and may cost you next time around if ignored.
 

Tyres and MOT Failure: Final Thoughts

Tyres are not just a tick box on your MOT – they’re critical to your safety.

With regular maintenance and a keen eye, you can stay compliant with the law and avoid a costly fail.

Whether it’s tread depth, sidewall condition or a TPMS warning light, don't leave tyre checks until MOT day.

The sooner you spot a problem, the easier – and cheaper – it’ll be to fix.