Written by the fitting team at 24/7 Mobile Tyre Services, Glasgow. Between us we have spent years on Scottish roads, driveways and test centre car parks. Last reviewed: July 2026. All DVSA rules quoted here were checked against current gov.uk guidance on the review date.
You are standing in a reception off Paisley Road West with a VT30 refusal sheet in your hand. The tester has written something about tread depth. The car is sitting outside. Your first two thoughts are the same two thoughts everybody has: am I even allowed to drive this home, and have I just been talked into four new tyres I do not need?
Here is the short version before anything else. Whether you can drive depends on one single word printed on that sheet. And tyres happen to be one of the few failure items that qualify for a free next working day retest, which most drivers are never told about.
Both of those are worth money to you today. The rest of this page explains exactly how to use them.
Quick answer: If your car failed its MOT on tyres, check whether the defect is marked dangerous or major. A dangerous defect means you must not drive the car at all. A major defect means you may only drive to a pre booked repair or retest, and only if your old MOT certificate is still valid.
First, read the one word that decides everything
DVSA grades every fault into three categories. Most people never learn them until the day they need them.
| Category | What it means | Can you drive? |
|---|---|---|
| Minor | Noted as an advisory. Car still passes | Yes |
| Major | Fail. Must be repaired | Only to a pre booked repair or retest, and only with a valid MOT still in date |
| Dangerous | Fail. Direct risk to safety | No. Not one mile |
Now match that to what testers actually write on tyre failures.
- Tread below 1.6mm usually comes out as major, though a badly worn tyre can be graded dangerous
- Cords or ply exposed is dangerous, every time
- Sidewall bulge or lump is dangerous
- A cut deep enough to reach the cords is dangerous
- Tyre fouling the bodywork, or the wrong fitment for the vehicle can be either, depending on severity
- TPMS warning lamp inoperative or faulty is a major
One legal point worth taking seriously. Driving on an illegal tyre carries a fine of up to £2,500 and 3 penalty points. That is per tyre, not per car. Four illegal tyres turns a short drive home into a potential £10,000 lesson and a licence you no longer hold.
But my MOT certificate is still in date, so I am fine?
This is the trap that catches careful, law abiding drivers.
Yes, a certificate that has not yet expired lets you drive away from a major fail. What it does not do is make the car roadworthy. Roadworthiness is a separate legal duty and it applies every second the car is moving.
A dangerous defect kills that argument completely. If a Police Scotland officer looks at a tyre with cords showing, the paperwork in your glovebox is not part of the conversation.
Why your tyres failed: decoding the wording on the VT30
The inspection manual language is precise, which is helpful once you know what it means. Here are the failures we see written up most often.
Tread depth below requirement. UK law sets the minimum at 1.6mm across the central three quarters of the breadth, around the entire circumference. That applies to cars, light vans and trailers up to 3,500kg.
That phrase “central three quarters” is the part almost nobody understands. A tyre can look fine at the shoulder and be bald in the middle grooves, or the reverse. The law only measures the middle band. This is exactly why a quick glance at a tyre fools experienced drivers.
Tyre worn unevenly. This one is a message about the car, not the tyre. Uneven wear points to tracking, camber or long term pressure problems.
Replace the tyre without fixing the cause and you will be back in the same reception next year, reading the same sentence.
Tyre cut, bulge or lump. Usually a kerb strike or a pothole. In Glasgow, overwhelmingly a pothole. We cover what to do about that in our guide on pothole damage to two tyres at once.
Tyres of different sizes or structures on the same axle. Mixing a radial with a cross ply, or two different sizes across one axle, is an automatic fail. No discretion involved.
Tyre not correctly seated on the rim. Often a hint that the last fit was rushed or the bead seat is corroded.
TPMS malfunction. Mandatory MOT item on any vehicle first used from 1 January 2012. A lamp stuck on the dash is enough to fail. If that is your situation, TPMS sensor replacement is usually a far smaller job than people expect.
The 20p test, and why it quietly lets people down
The 20p coin trick is genuinely useful. It is just not a legal test.
The outer band of a 20p sits at roughly 3mm, which gives you a warning margin, not a pass mark. A tyre that looks fine against a coin at the shoulder can still be under 1.6mm in the centre grooves where it counts.
Use a proper depth gauge. Or ask any fitter to check it for you, which most of us will do without charging.
The retest rule most drivers are never told about
This is where the money is, so read this section twice.
| Your situation | What the retest costs |
|---|---|
| Leave the car at the test station, repaired there, retested within 10 working days | Free |
| Take the car away, repair it, return to the same station before the end of the next working day, for eligible items including wheels and tyres | Free |
| Take the car away, return to the same station within 10 working days | Partial retest fee, commonly up to half the test fee |
| Return after 10 working days, or go to a different station | Full MOT again, up to £54.85 for Class 4 |
Read the second row again. Wheels and tyres sit on the DVSA list of items eligible for a free partial re examination, provided the vehicle comes back to the same station before the end of the next working day.
That single rule changes the maths entirely.
Fail on Tuesday afternoon. A fitter attends your driveway in Bishopbriggs on Tuesday evening. You drive back to the same station on Wednesday morning. Retest fee: nothing.
Compare that to the usual route, where the car stays at the garage, the garage fits the tyres, and you collect it two days later having lost a day of work and a bit of choice over what went on your wheels.
The catch nobody mentions
Three conditions, and all three must hold.
- It must be the same testing station, under the same ownership
- The vehicle must return before the end of the next working day
- Working days exclude weekends and bank holidays, so a Friday afternoon fail gives you until close of business on Monday
One piece of practical advice we give every customer in this situation: ring the test station and provisionally book the retest slot before your fitter even arrives. Slots at busy Glasgow stations go quickly, and there is no point in getting the tyres sorted at 7pm if there is no space to re present the car the next day.
If the defect was dangerous, you cannot drive the car to a fitter
That is the awkward bit of the rule. A dangerous defect means the car does not move, which rules out driving it to a tyre shop.
The car cannot come to the tyres, so the tyres have to come to the car. That is the whole reason mobile tyre fitting in Glasgow exists, and it is why a fair share of our callouts start in a test centre car park.
Do you actually need all four tyres?
Sometimes yes. Often no. Both answers are legitimate, and it is worth knowing how to tell them apart.
Legitimate reasons a tester or garage suggests more than the failed item:
- The other tyre on the same axle is at 2mm and will be illegal in a few months
- Grip is genuinely mismatched across an axle, which affects braking balance in the wet
- An advisory has been recorded because something is close to the limit
The rule of thumb: an MOT only requires you to fix the failure items. Advisories are advice. They are worth listening to, but they are not law and they are not a deadline.
Before you agree to anything, do two things.
- Ask to be shown the failed tyre. Any honest tester or fitter will walk you out to the car
- Photograph each sidewall. You want the size, load index, speed rating and DOT code
Those photos protect you. They let you price the job accurately with anyone, and they stop a conversation drifting from two tyres to four without an explanation.
Worth reading next if this is your situation: what to do when a garage says you need four new tyres and when good tread does not mean a good tyre.
What this costs in Glasgow, and where the money actually goes
We deliberately do not publish fixed prices, because tyre prices move constantly and a stale number on a webpage helps nobody. What we can do is show you the parts of the bill so you can read any quote properly.
A tyre job is made up of:
- The tyre itself, which is where nearly all the price variation lives (budget, mid range, premium)
- Fitting
- Wheel balancing, which should never be optional
- A new valve, cheap and worth insisting on
- Disposal of the old tyre
- A callout charge, if the fitter travels to you
Now compare the two routes honestly.
Garage path: you leave the car, you take the garage’s margin on whatever tyres they stock, you may lose a working day, and if the timing slips past the next working day you pay a retest fee on top.
Mobile path: the fitter comes to the driveway, the office car park or the test centre itself, you lose no day, and the free retest window stays intact.
One last honest word on brands. Premium is not automatically the right answer, and budget is not automatically a trap. What matters far more for a car that passes and drives well is matched pairs across an axle and the correct load index and speed rating for your vehicle. A correctly specified mid range tyre beats a mismatched premium one every time.
The 30 minute action plan
- Photograph the VT30 and look for the word “dangerous”
- Ring the test station and provisionally book tomorrow’s retest slot
- Photograph each tyre sidewall: size, load index, speed rating, DOT week and year
- Get your quote using the size on the sidewall, not the size in the handbook. Previous owners change tyre sizes more often than you would think
- Book a fitter who can attend today, at wherever the car is currently sitting
- Confirm the fitter balances the wheel, fits a new valve and torques to manufacturer spec before they leave
- Return to the same station before close of the next working day
A job that stuck with us
A customer failed on two tyres at a Southside test station on a wet Thursday afternoon. One was marked dangerous, so the car was going nowhere.
She rang us from the reception desk. We were in the test centre car park inside the hour, fitted both, balanced them, torqued to spec and checked the pressures. She re presented the car the next morning at the same station.
Retest cost her nothing. Total time lost from her working week: about ninety minutes, most of which she spent on her laptop in the waiting area.
That is not a clever trick. It is just the rule being used the way it was written.
FAQs
Can I drive my car home if it failed the MOT on tyres? Only if the defect is graded major and your existing MOT certificate is still in date. If any tyre defect is marked dangerous, the car must not be driven at all, regardless of what certificate you hold.
Is the MOT retest free if it only failed on tyres? It can be. Wheels and tyres appear on the DVSA list of items eligible for a free partial re examination, provided you return the vehicle to the same test station before the end of the next working day. Leaving the car at the station and having it retested within 10 working days is also free.
How long do I have to get the tyres replaced? Legally, the car must be roadworthy before it is driven again, so with a dangerous defect the answer is immediately. For the free retest, your window is the end of the next working day at the same station.
What is the minimum legal tread depth in the UK? 1.6mm across the central three quarters of the tyre’s breadth, around its entire circumference. This applies to cars, light vans and trailers up to 3,500kg.
Will a part worn tyre pass an MOT? It can, if it meets the tread and condition requirements and was legally sold under the part worn regulations. In practice, part worns often come with unknown history and internal damage you cannot see, which is why we rarely recommend them.
Does the MOT check tyre age? Not for ordinary cars. There are age rules for certain older buses and coaches. That said, tyres degrade with time as well as use, and a ten year old tyre with plenty of tread can still be a genuine safety risk. We covered that separately in our guide on old tyres with good tread.
Can you fit tyres at the MOT centre car park? Yes, and we do it regularly across Glasgow. As long as there is safe space to work and the site is happy for us to be there, we can fit on the spot so you keep your retest slot.
What happens if I just don’t fix it? The car stays unroadworthy. Driving it risks up to £2,500 and 3 penalty points per illegal tyre, and your insurer may treat a known unroadworthy defect as a reason to challenge a claim.
If your retest window is running down
If the car cannot legally move and the clock on your free retest is ticking, we will come to it. Driveway, office car park, layby or the test centre itself, anywhere in Glasgow and across Scotland, 24 hours a day.
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Call 07955 533000 or message us on WhatsApp.
