Is a Slow Puncture an MOT Failure?
Updated 14 October 2026 · Hyde Road Wheels & Tyres team
Key facts
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Under-inflated tyre: “Tyre obviously under-inflated” is listed as a minor defect. Source: GOV.UK MOT inspection manual, www.gov.uk/guidance/mot-inspection-manual-for-private-passen (page updated 1 June 2026)
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Warning system fault: “Tyre pressure monitoring system malfunctioning or obviously not working” is a major defect, and major defects fail the test. Source: same manual page.
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What is tested: tyre condition, security, size and type, and tread depth. Source: GOV.UK, www.gov.uk/government/publications/car-parts-checked-at-an-m
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TPMS check: cars first used on or after 1 January 2012 are checked to make sure the tyre pressure monitoring system warning light is working. Source: same GOV.UK page.
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Tread: tread depth not in accordance with the requirements is a dangerous defect. Source: GOV.UK manual page above.
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Routine check: the Highway Code says to check tyre pressures weekly, before the journey, when tyres are cold. Source: www.gov.uk/guidance/the-highway-code/annex-6-vehicle-mainten
What does the MOT check on tyres?
The tester inspects the condition and security of each tyre, its size and type, and its tread depth. Spare wheels and tyres are not inspected. On newer cars the tester also checks the pressure monitoring system warning light.
Will a slow puncture fail the MOT?
Not by itself. An obviously under-inflated tyre is a minor item in the manual, so it appears on the certificate as something to deal with, not as a fail. A test is not designed to find a leak that has not yet gone flat.
The danger is a slow leak that has already left the tyre damaged or worn. Tread depth below the requirement is rated dangerous, and a damaged tyre is judged on its condition, not on the leak that caused it.
Does the tyre pressure warning light fail an MOT?
A light that is not working is the problem. The manual rates a pressure monitoring system that is “malfunctioning or obviously not working” as major. A light that comes on because a tyre is low is the system doing its job, but it is still a prompt to find the cause before you book.
What causes a slow puncture?
A slow puncture can come from a nail or screw in the tread or from a damaged valve. TyreSafe says a repairable slow puncture is usually fixed with a patch or plug from the inside, or by replacing the valve (https://www.tyresafe.org/tyre-advice/tyre-care-repair/punctures-and-puncture-repairs/). Which one it is decides the repair, so the fix starts with finding where the air is going.
Fix first or test first?
Fix first. Pump the tyre to the pressure in your handbook, mark where it sits after a day or two, and have a garage find the leak. Then book the test. Arriving with a repaired tyre avoids a retest and a wasted visit.
Slow puncture or flat tyre?
| Slow puncture | Flat tyre | |
|---|---|---|
| Pressure | Falls over days or hours | Gone quickly |
| Manual rating if merely low | Minor (obviously under-inflated) | Judged on the tyre’s condition and damage |
| Next step | Find the leak and fix it | Do not drive on it; get it inspected |
Slow punctures in Gorton
At Hyde Road Wheels & Tyres in Gorton we test cars at our MOT station and repair punctures in the same building at 270 Hyde Road, Manchester M12 5FH. If your tyre is losing air before a test, bring it in and we will find the cause. See our tyre repair service in Manchester for details. We are open Monday to Friday 9:00 to 17:30 and Saturday 9:00 to 16:30.
Tyres are on the failure list: see why cars fail the MOT. If the damage is near the edge of the tyre, read can a sidewall puncture be repaired.
Frequently asked questions
Will the MOT tester notice a slow puncture?
Only if the tyre is obviously under-inflated or damaged on the day. The manual rates an obviously under-inflated tyre as minor.
Can I drive to the MOT with a slow puncture?
Top up to the correct pressure first and check it again before you set off. If the tyre will not hold air, have it inspected before driving.
Does a warning light fail the MOT?
A pressure monitoring system that is malfunctioning is a major defect. Check the light works and that no fault is showing.
Does the spare tyre get tested?
No. GOV.UK says spare wheels and tyres are not inspected.
What should I do before the test?
Check pressures when the tyres are cold, look at the tread and sidewalls, and fix any leak before you book.
Need tyres, an MOT or a repair in Gorton?
Ring the garage on 0161 274 3125 or come to 270 Hyde Road. We will tell you what the car needs before any work starts.
Hyde Road Wheels & Tyres, 270 Hyde Road, Gorton, Manchester M12 5FH. Open Mon to Fri 9:00 to 17:30, Sat 9:00 to 16:30.