Yes, your car will definitely fail its MOT if the tyre tread is below the legal 1.6mm minimum, or if it has serious cuts, lumps, or bulges. However, minor wear or ageing might only result in a pass with an advisory notice.
It's one of the most common questions I get asked as an MOT tester: 'Will my car fail on its tyres?' It's a sensible thing to worry about. Your tyres are the only things connecting your car to the road, and their condition is absolutely critical for your safety, especially when it comes to braking and cornering in the wet. The rules around tyres for the MOT aren't just about how much tread you have left. We look at the tyre's entire condition, and a failure can come from several different issues, some of which aren't obvious at a quick glance. Lots of people get caught out by uneven wear on the inside edge of a tyre, or by damage they picked up from a kerb or pothole weeks ago and have since forgotten about. Understanding what we look for during the test can save you the hassle and expense of a failure. A fail for tyres isn't just an inconvenience; if a defect is classed as 'dangerous', you won't be able to legally drive the car away from the test centre. Let's break down the official rules and what they mean in the real world, so you can go into your next MOT with confidence.
The official UK MOT rule
When we inspect your car, we're not just making it up as we go along. We follow a strict set of guidelines laid out by the Driver and Vehicle Standards Agency (DVSA). For cars (Class 4 vehicles), the relevant rules are in **Section 5.2.3 of the MOT inspection manual**. Here’s what the rulebook says, in plain English: **1. Tread Depth:** This is the big one. The law requires a minimum tread depth of **1.6mm**. But it's not quite that simple. This depth must be present in a continuous band across the *central three-quarters* of the tread's width and around the *entire circumference* of the tyre. This means if you have one spot on the inside edge that's worn smooth, even if the rest of the tyre looks fine, it's a fail. We use a DVSA-approved, calibrated tread depth gauge to measure this precisely. **2. Lumps, Bulges and Tears:** A lump or bulge on the side of a tyre is an immediate red flag. It almost always indicates that the internal structure of the tyre has failed, often due to an impact with a kerb or pothole. This is extremely dangerous as it can lead to a catastrophic blowout. The manual is very clear: a 'lump, bulge or tear caused by separation or partial failure of the tyre's structure' is a **Dangerous Defect**. **3. Cuts and Exposed Cords:** Your tyre has layers of fabric or steel cords underneath the rubber tread. If you have a cut on your tyre deep enough for these cords to be visible, it's a **Major Defect** and a straight fail. Even if the cords aren't visible, a large, deep cut over 25mm or 10% of the tyre's width could still be a fail if it's deemed deep enough to have reached the ply. **4. Fouling:** The tyre must not be fouling (rubbing against) any part of the vehicle's bodywork or a brake pipe or hose under any steering condition. We check this by turning the steering from full lock to full lock. **5. Tyre Pressure Monitoring System (TPMS):** If your car was first used on or after 1st January 2012, it's fitted with a TPMS. If the warning light is o
How testers actually assess this
When your car comes into the bay, the tyre inspection is one of the most hands-on parts of the test. We can't do it properly just by looking. We need to get up close and personal with every tyre on the vehicle. First, we do a general visual check as the car comes in. Then, once it's on the ramp, the detailed work begins. I'll take my tread depth gauge and check each tyre in several places. I don't just measure the middle; I measure across the width of the tread pattern, in the main grooves, to check for that 'central three-quarters' rule. People often get caught out by poor wheel alignment causing the inside or outside edge to wear much faster than the rest of the tyre. You might check your tyres and think they look great from the outside, but the inner edge could be completely bald and illegal. Next, I run my hands around the entire surface of the tread and both the inner and outer sidewalls. I'm feeling for anything unusual. My fingers can detect subtle lumps or deformities that the eye might miss. I'm also feeling for embedded objects like nails or screws, and checking for any cuts or splits in the rubber. This is why we wear gloves – you'd be amazed what can be stuck in a tyre! We pay very close attention to the inner sidewall, the side you can't see. This area is often damaged by rubbing against a worn suspension component, something you'd never notice from a casual walk-around. With the car on the ramp and the steering turned, we get a clear view of the whole tyre. Finally, we consider the overall picture. Are the tyres on the same axle of the same size and type? For example, you can't have a radial-ply tyre on one side of an axle and a cross-ply on the other. Do the tyres look severely aged and perished, with lots of small cracks in the rubber? While age itself isn't a reason for failure, advanced perishing can be. The assessment is a combination of precise measurement and experienced judgement, all guided strictly by the DVSA manual. It's thorough, consisten
Common scenarios — pass, advisory or fail?
Let's walk through some real-world examples I see every week in the test bay. This will help you understand the difference between a pass, an advisory, and a fail. * **Scenario 1: Tread is getting low.** You check your tyres and the tread seems okay, but it's not brand new. I measure it with my gauge and find it's 2.5mm across all tyres. * **Result: PASS, with an advisory.** The legal limit is 1.6mm, so at 2.5mm you are perfectly legal and safe for now. However, that's not a lot of tread left before you hit the limit. I'll add an advisory note like: `[001] Tyre worn close to legal limit/worn on edge [5.2.3 (e)]`. This is just a friendly warning to you that you'll need to think about replacing them in the coming months. * **Scenario 2: A small nail in the tread.** During the inspection, I find a screw head sat flush in one of the main tread grooves. It doesn't appear to be losing air. * **Result: PASS, with an advisory.** As long as the tyre isn't deflated and there are no lumps or bulges around the nail, it isn't an MOT fail. The structure of the tyre isn't compromised. However, I will absolutely advise you about it. The advisory will say something like `Tyre has a nail in it`. This alerts you to the fact you should get it properly repaired (plugged) at a tyre specialist before it works its way deeper or causes a slow puncture. * **Scenario 3: Uneven wear on a front tyre.** The outside two-thirds of your tyre has a healthy 4mm of tread. But the inner third, right on the inside shoulder, is completely smooth and the tread wear indicators are flush with the surface (so it's below 1.6mm). * **Result: FAIL (Major Defect).** This is a very common failure. The rule requires 1.6mm across the *central three-quarters*. If any part of that band is below the limit, the entire tyre fails. It's also a strong sign your wheel alignment (tracking) is out, so you should get that checked when you replace the tyre to avoid the new one wearing out just as quickly. * **Scenario 4: A bul
What to do if you're worried before your test
It's always better to find a problem yourself a week before the MOT than for me to find it during the test. A few simple checks can save you a lot of time and money. Here’s what you can do: **1. The 20p Test:** This is a brilliant, simple way to get a rough idea of your tread depth. Take a 20p coin and place it into the main tread grooves of your tyre. The border of the 20p piece has an outer band on it. If you can't see that outer band when the coin is in the groove, your tread is likely above the 1.6mm legal limit. If you *can* see the band, your tread is getting low and you should have it checked properly with a gauge. Make sure you do this in several places across the tyre's width and at different points around its circumference. **2. A Good Look and Feel:** Turn your steering wheel to full lock one way, then the other. This will give you a clear view of the entire width of your front tyres. Look for any obvious cuts, cracks, or embedded objects. More importantly, run your hands (carefully!) over the sidewalls (inner and outer) and across the tread. You're feeling for any lumps, bulges, or scuffs. Your fingertips are surprisingly good at detecting problems. **3. Check for Ageing:** Look at the sidewalls for signs of perishing. This looks like a network of fine cracks in the rubber surface. While minor cracking might only get an advisory, deep, widespread cracking could indicate the rubber has hardened and is no longer safe. **4. Check Your Pressures:** Although incorrect pressure isn't a fail in itself (unless the TPMS light is on), it's vital for tyre longevity and safety. Consistently low pressure will cause wear on the outer edges, while over-inflation wears the centre. Check the pressures when the tyres are cold, using the figures printed inside your driver's door jamb or fuel flap. If you do any of these checks and you're not sure what you're seeing, don't guess. Pop into any local tyre garage. Most will offer a free, no-obligation tyre safety check.
What happens if you do fail
Okay, so the worst has happened, and I've had to fail your car on a tyre. Don't panic, it's a common situation and there's a clear process to follow. You'll be issued with a VT30 'Refusal of an MOT Test Certificate', which lists the reason for failure. Tyre defects are categorised as either 'Major' or 'Dangerous'. * **If it's a 'Major Defect'** (e.g., tread below 1.6mm), your car has failed its MOT. You can't get a new certificate until it's fixed. If your previous MOT certificate is still valid, you can technically drive the car away to be repaired. However, be aware that you are knowingly driving a vehicle with a defect that makes it unroadworthy, which could land you in trouble with the police (fines and points) if you're stopped. The safest option is always to have it repaired before driving it. * **If it's a 'Dangerous Defect'** (e.g., a large bulge or exposed cords), the situation is more serious. The law is very clear: you **cannot** drive a vehicle with a dangerous defect on the road. Your VT30 will be marked accordingly. The only exception is driving it to a pre-arranged appointment to have the defect repaired, but a tyre is something that can almost always be fixed on-site by a mobile fitter or at the garage. You absolutely cannot drive it home or to the shops. **Getting a Retest:** You have a couple of options for the retest. 1. **Leave it with us:** If you leave the car at the test station to be repaired and we retest it within 10 working days, we only need to do a partial retest to check the tyre. This is usually free of charge. 2. **Take it away for repair:** You can take the car somewhere else for a new tyre. If you bring it back to the *same test centre* for a retest before the end of the next working day, the partial retest is also free. If you bring it back within 10 working days, you will pay a reduced fee for the partial retest. After 10 working days, you'll need a full MOT test again at the full price.
Are 'budget' tyres more likely to fail an MOT? — Not because of their brand, no. Any new tyre sold in the UK, budget or premium, must meet strict safety standards to be legal. It will pass an MOT perfectly fine when new and correctly fitted. The difference between budget and premium tyres is usually found in performance—things like wet grip, road noise, and how long they last. A cheap tyre on a car with bad alignment will wear out just as fast, if not faster, than an expensive one. We test for condition and safety, not the price tag.
My TPMS (tyre pressure) warning light is on. Is that an MOT fail? — Yes, if your vehicle was first used on or after 1st January 2012. For these vehicles, a Tyre Pressure Monitoring System (TPMS) warning light that stays on indicates a system malfunction, and this is a 'Major Defect' which will fail the MOT. This is covered in Section 5.2.3 of the inspection manual. If your car is older than that, the TPMS system is not part of the test, but the light is still warning you of a problem that you should get checked for your own safety.
What about the spare tyre? Is that part of the MOT test? — It depends entirely on where it's stored. If you have a spare wheel in the boot or secured inside the car, it is not inspected as part of the MOT. However, if your spare wheel is carried in a cradle underneath the vehicle, then we are required to check it. We inspect the tyre for its general condition and security, and also check that the mounting cradle itself is not corroded or insecure. A defective spare or cradle in this position can be a reason for failure.
My tyres are over 10 years old but look fine. Can they fail for their age? — For a car, there is no MOT rule that fails a tyre based solely on its date of manufacture. However, age is a factor we consider. Very old tyres can suffer from rubber perishing, which presents as fine crazing or cracking on the sidewalls. If this cracking is minor, it will likely be a 'pass with advisory'. If the cracks are deep and extensive enough to expose the tyre's cords or compromise its structure, it would fail. So an old tyre doesn't automatically fail, but its age-related condition might.