The MOT test is stressful enough without discovering your tyres have failed at the last minute. Understanding exactly what MOT testers look for in your tyres helps you prepare properly and avoid that sinking feeling when you collect your car and see “FAIL” on the certificate.
Tyre-related failures are among the most common MOT issues, yet they’re also the most preventable. Let’s break down exactly what your tyres need to pass the test.
The Legal Minimum Tread Depth
This is the big one. Your tyres must have at least 1.6mm of tread depth across the central three-quarters of the tyre, all the way around its circumference. The MOT tester will check multiple points on each tyre.
If any part of any tyre is below 1.6mm, that’s an immediate MOT failure. No debate, no second chances. You’ll need to replace the tyre before you can retest.
Don’t cut it fine. If your tread is sitting right at 1.6mm, it might measure below that by the time you get to the test centre. Aim for at least 2mm before your MOT to give yourself a safe margin.
The tester uses a proper depth gauge, not just eyeballing it. Those worn tread wear indicators (the small bars in the tyre grooves) show when you’ve hit 1.6mm, but by that point you’re already at the legal limit with no room for error.
Tyre Damage That Causes MOT Failure
Tread depth isn’t the only concern. The MOT tester examines your tyres thoroughly for any damage that could affect safety.
Cuts or bulges in the tyre are serious defects. Any bulge, regardless of size, means instant failure. Bulges indicate internal structural damage, and the tyre is considered dangerous. Cuts that are deep enough to expose the cords or are larger than 25mm long will also fail.
The tester checks both the tread area and the sidewalls. Many people focus on tread depth and miss sidewall damage that will fail them just as quickly.
Objects embedded in the tyre get assessed case by case. A small stone wedged in the tread probably won’t fail you, but anything that’s penetrated through the tyre or caused visible damage will. Don’t risk it. Get punctures assessed and repaired before your MOT.
Incorrect Tyre Types and Mismatched Sizes
Your tyres must be suitable for your vehicle. You can’t fit car tyres to a van, or use tyres with inadequate load ratings. The MOT tester checks that your tyres match your vehicle’s requirements.
Mixing radial and cross-ply tyres is illegal and will fail the MOT. In practice, cross-ply tyres are rare on modern cars, but if you’re running an older vehicle, this matters.
All tyres on the same axle must be the same size and type. You can’t have mismatched tyres on the front axle or rear axle. Different tyres front to rear is usually acceptable, but both fronts must match each other, and both rears must match each other.
If you’ve had an emergency tyre fitted and it’s a different size or type to what should be on the car, get it sorted before the MOT. The tester has no flexibility on this.
Tyre and Wheel Condition Issues
The condition of the tyre’s seating on the wheel matters too. If the tyre isn’t seated properly on the rim, that’s a failure. This can happen after a poor tyre fitting or if you’ve had a puncture and the tyre has partially come off the rim.
Exposed cords anywhere on the tyre, whether from wear or damage, are an automatic fail. If you can see the fabric structure of the tyre through worn tread or damaged rubber, it’s failed before the tester even measures the depth.
Tyres with large cracks in the rubber, especially in the sidewalls, can fail the MOT. Surface crazing might get through, but deep cracks that indicate rubber degradation won’t. Age-related cracking is a common failure point on cars that don’t do many miles.
Valve and TPMS Requirements
Your tyre valves must be in good condition with dust caps fitted. Missing valve caps aren’t always a failure, but damaged valves or valves that are leaking will fail you.
If your car is fitted with a Tyre Pressure Monitoring System (TPMS), it must be working correctly. The TPMS warning light on your dashboard must not be illuminated. This became part of the MOT test in 2015 for cars fitted with TPMS as standard.
Some people remove TPMS sensors when fitting new tyres to save money. If your car came with TPMS, removing it will cause an MOT failure. The system needs to be present and functioning.
Spare Tyres and Space Savers
Here’s some good news: your spare tyre isn’t checked during the MOT. Whether you have a full-size spare, a space-saver, or no spare at all makes no difference to passing or failing.
However, don’t let this fool you into neglecting your spare. You might pass your MOT with a flat or damaged spare in the boot, but you’ll regret it when you need it on the side of the motorway.
Space-saver spare tyres have specific restrictions (usually 50mph maximum and limited distance), but these aren’t MOT concerns. Just make sure you’re not actually driving on a space-saver when you turn up for the test, as it won’t be legal for normal use.
How Old Tyres Affect Your MOT
There’s no specific age limit for tyres in the standard MOT test. A tyre could be ten years old and still pass, provided it meets all the other requirements for tread depth and condition.
However, older tyres are more likely to have cracking and deterioration that will cause failure. The rubber compounds degrade over time, and this visible degradation can fail your MOT even if the tread depth is adequate.
For certain vehicles (buses, coaches, and lorries), tyres over ten years old cannot be used on front axles. This doesn’t apply to standard cars and vans, but it shows the safety concerns around old tyres.
Tyre Pressure and MOT Testing
Interestingly, tyre pressures are not specifically tested during an MOT. The tester isn’t required to check whether your tyres are inflated to the correct pressure.
That said, obviously under-inflated tyres might raise concerns about damage or condition. A tyre that’s completely flat will likely get a closer inspection for sidewall damage caused by driving on it.
Even though pressure isn’t tested, you should still ensure your tyres are properly inflated before the MOT. It makes the car easier to manoeuvre during the test and ensures the tester can properly assess tread wear patterns.
Different Rules for Vans and Commercial Vehicles
If you’re taking a van or light commercial vehicle for its MOT, be aware that the tyre requirements can be stricter. Commercial tyres often need to meet higher load ratings, and the acceptable tread depth might differ in some circumstances.
Vans are also more likely to show uneven wear due to heavy loading, which can cause failures even if some parts of the tyre are above the legal limit. The entire tyre needs to meet the standard, not just the best-wearing section.
Preparing Your Tyres for the MOT
Check your tyres properly at least a week before your MOT is due. This gives you time to get replacements or repairs sorted without the stress of rushing around the day before.
Walk around the car and look at each tyre carefully. Check the tread depth at multiple points using a depth gauge or the 20p test. Look for any damage, bulges, or cracks. Make sure all valve caps are present.
If anything looks borderline, get it checked professionally. An MOT failure means you’ll need to pay for a retest after fixing the issue. It’s cheaper and less hassle to sort problems beforehand.
What Happens If Your Tyres Fail
A tyre-related failure means you’ll get a red “dangerous” marker if it’s a serious issue like exposed cords or major damage, or an amber “major” marker for things like insufficient tread depth.
You cannot legally drive the car on public roads until the defect is fixed, unless you’re driving directly to have the repairs carried out. Most people get the tyres replaced at the test centre or arrange for mobile fitting.
Once the tyres are replaced, you’ll need a partial retest. The fee for this is usually less than a full MOT, but you’re still paying extra because you didn’t prepare properly.
How Mobile Tyre Services Help with MOT Preparation
If you’re concerned about your tyres before an MOT, mobile tyre services offer a convenient solution. We can inspect your tyres at home or work, give you an honest assessment of whether they’ll pass, and fit replacements on the spot if needed.
This is particularly useful if you’ve already booked your MOT appointment. Rather than risking a failure and retest, you can get your tyres sorted beforehand at your convenience.
DC Emergency Tyre Fitting provides pre-MOT tyre inspections and replacements across Barnsley, Rotherham, Sheffield, Doncaster, and Wakefield. We’ll ensure your tyres meet all MOT requirements, saving you the hassle and cost of a preventable failure.
