MOT Tyre Requirements: What the Examiner Checks and Common Failures
Tyres are one of the most common reasons for MOT failure in the UK. Understanding exactly what the examiner checks can help you avoid a failed test and the inconvenience of rescheduling. If your MOT is coming up in {location}, here's what you need to know.
What the MOT Examiner Checks
The tyre inspection is thorough and covers several specific areas:
Tread depth: The legal minimum is 1.6mm of tread across the central three-quarters of the tyre's breadth, around its entire circumference. The examiner will use a calibrated tread depth gauge, not a visual estimate.
Tyre condition: The examiner looks for cuts, bulges, lumps, tears and any damage that exposes the internal structure (cords or plies). A bulge on the sidewall is an immediate failure, as is any cut deep enough to reach the cords.
Correct size and type: All tyres on the same axle must be the same size, aspect ratio, speed rating and construction type. You cannot mix radial and cross-ply tyres on the same axle. Mixing tyre sizes across axles is acceptable in some cases but must match the vehicle manufacturer's specification.
Speed rating: Each tyre must have a speed rating that meets or exceeds the vehicle manufacturer's minimum requirement. Fitting a tyre with a lower speed rating than specified is an MOT failure.
Tyre pressure monitoring system (TPMS): For vehicles first registered from January 2012 onwards, the TPMS must be functioning correctly. A TPMS warning light on the dashboard is an MOT failure.
Most Common Tyre-Related MOT Failures
- Insufficient tread depth: By far the most common tyre failure. Often caught on inner edges that the driver doesn't easily see without getting underneath the car.
- Sidewall damage: Bulges from kerb impacts are the usual culprit. Many drivers don't notice a sidewall bulge until it's pointed out.
- Mismatched tyres on an axle: Two different sizes or mixing speed ratings on the same axle.
- TPMS malfunction: The warning light stays on because a sensor battery has died or a sensor was damaged during a previous tyre change.
- Perished rubber: On older vehicles that aren't driven frequently, the rubber can crack and degrade even with good tread remaining.
Advisory vs Failure
Not every tyre issue results in a failure. The examiner may issue an advisory notice for tyres that are legal but approaching the limit. An advisory is not a failure — your vehicle still passes — but it's a clear signal that replacement is needed soon. Ignoring advisories is a false economy.
How to Prepare for Your MOT
- Check tread depth on all four tyres, including the inner edges — get down low and look at the full tread surface
- Inspect sidewalls for bulges, cracks and cuts on both inner and outer faces
- Verify that both tyres on each axle are the same size by reading the sidewall markings
- Check that your TPMS warning light is not illuminated (if your car has TPMS)
- Ensure tyre pressures are correct — the examiner notes this too
What to Do Before Your Test
If you find any issues, visit a tyre fitter in {location} before your MOT appointment. Replacing a borderline tyre before the test is cheaper than failing, paying a retest fee, and then replacing the tyre anyway. Most tyre fitters can check your tyres and fit replacements within an hour, so there's no need to delay your MOT by more than a day.