Tyre sidewall damage: is it safe, is it legal, and can it be repaired?

Whether sidewall damage is safe depends on how deep it goes. The table below sorts the common marks into three outcomes: cosmetic, get it checked, and replace now.

This guide shows how to tell the difference at the kerb, what an MOT tester checks, what the law says and what to do next. The legal points come from the Construction and Use Regulations and the DVSA MOT inspection manual. The repair rules come from the BTMA summary of BS AU 159, the British Standard for tyre repairs. All the sources are listed at the end.

Types of tyre sidewall damage and what each one means

The sidewall is the smooth band between the tread and the wheel rim. It carries the weight of the car and flexes on every turn of the wheel. A mark that would not matter on the tread can matter a great deal here. Sort what you see into one of three outcomes.

How much damage in a tyre sidewall is OK?

Say you have clipped a kerb while parking and there is a pale scuff on the sidewall. Is that OK? Damage that stays in the outer rubber usually is; damage that reaches the cords underneath is not, whatever its size. The cords are the fabric or steel layer that holds the air pressure in. Rubber over them is protection, and a kerb scuff that only takes off some of that rubber is usually harmless. If marks are numerous or deep, though, Michelin advises having them examined rather than judging them yourself.

Things that move a mark from cosmetic to unsafe:

• Any fabric, threads or wire visible in the bottom of the mark.
• A cut that gapes open when you press the rubber either side of it, or one you could slide a fingernail into.
• Any raised area next to the mark, however small.
• Cracks deep enough to open up when you press beside them.
• Damage at the rim edge or bead, where the tyre seals onto the wheel.

A small cut in the tyre sidewall

Size is not what decides it. In the MOT, any ply or cord a tester can see fails irrespective of the size of the cut, according to the MOT inspection manual. A small cut that has not reached the cords is a mark to watch; a small cut with cord showing at the bottom is a replacement. Do not dig into it with a key or screwdriver to find out: you can make it worse, and a fitter has the tools to open it without doing more damage.

Check the inner sidewall too

Michelin points out that cuts and bulges can be on the inner sidewall, the side facing under the car, where a walk round will not show them. For a front tyre, turn the steering to full lock and use a phone torch; for a rear tyre you may need to look from behind the wheel. A new vibration through the steering or seat after a knock is another sign worth acting on, because Michelin notes a bulge usually brings abnormal vibration.

What a fitter checks, and what to tell us on the phone

This is how a tyre fitter generally works through a damaged sidewall. You can do the first steps yourself before you ring anyone.

1. Both sides of the tyre. Outer wall, then the inner wall at full lock with a torch, all the way round.
2. The depth of any cut. Opened gently with a blunt tool, as MOT testers are told to do, to see whether cord is visible or can be felt.
3. Any raised area. Checked by eye and by running a hand round the wall, to tell a bulge from a normal dip.
4. The pressure. TyreSafe notes that hitting a kerb can damage the wheel rim as well as the sidewall, so a soft tyre may be losing air at the rim.
5. The wheel. The rim lip and spokes for bends, cracks and gouges that would damage a new tyre.
6. The partner tyre on the same axle. Tread depth and condition, to decide between one tyre and a pair.

If you ring us, these four things save time and mean the right tyre is on the van:

• Where the car is, and whether it is parked somewhere safe off the main road.
• The tyre size printed on the sidewall (for example 205/55 R16 91V), or the registration.
• What you can see: cut, bulge, cracks, cord showing, and which wheel. A photo on WhatsApp helps.
• Whether the wheels have locking nuts, and where the key is.

Can tyre sidewall damage be repaired?

No, not if the damage has reached the cords or casing: that tyre has to be replaced. British Standard BS AU 159, as summarised by the British Tyre Manufacturers' Association (BTMA), only allows a puncture repair in area T, the middle of the tread, for an injury no bigger than 6mm after the repairer has prepared it. The shoulder and the whole sidewall sit outside it. Area T is a share of the tyre's section width:

The same BTMA summary rules out a repair for splits, cuts or cracks that reach the casing, and for bead damage. Sidewall rubber separation and cords exposed by sidewall scuffing are on the same list. Michelin explains why: once the sidewall is cut or punctured, the tyre cannot get back the ability to flex that it needs. Our puncture repair page shows what can be fixed in the tread.

There is one honest limit to that. The BTMA summary does allow a surface filling on rubber-only damage anywhere on the outside of the tyre. That applies only where nothing has gone through and no ply is damaged. It tidies a scuff; it does not strengthen anything, so it is cosmetic.

The summary also sends larger injuries to an approved major repairer, a specialist repair firm. We could not confirm from the current standard whether any such repair applies to a car sidewall. A mobile fitter, us included, does not repair sidewalls.

Tyre wall repair kits, glue and crack fillers

Products sold as tyre wall repair kits, sidewall glue or tyre crack repair compounds can fill a mark so it looks better. They cannot rejoin cut cords or close a crack that reaches the casing. The BTMA does not recognise liquid sealants, plugs pushed in from outside, inner tubes in tubeless tyres or temporary repairs as repairs, and TyreSafe says plugs and sealants cannot be considered permanent. If something has already been used on the tyre, tell the fitter.

Is it safe to drive with sidewall damage?

With a scuff that stays in the rubber, yes. With a cut into the cords, a bulge or exposed cord, no. Michelin warns that if a bulge bursts while driving fast, for example on the motorway, the sudden loss of air can cause loss of control. The MOT manual classes a bulge or exposed cords as Dangerous, which DVSA defines as a direct and immediate risk to road safety.

If you find serious damage at home, leave the car where it is. If you find it on a journey, drive slowly to the nearest safe place to stop and go no further on that tyre. The Highway Code says to stop as soon as it is safe and only change a wheel if you can do so without risk to yourself or others.

If you are on a motorway

National Highways advises:

1. Leave at the next exit or pull into a service area if you can.
2. If you cannot, use an emergency area, a lay-by or the hard shoulder.
3. Get out on the side away from traffic and wait behind the safety barrier where there is one.
4. Call National Highways on 0300 123 5000, or 999 if there is an immediate risk to life.

The Highway Code says not to attempt repairs there. No one should change a wheel on a live carriageway, hard shoulder or slip road, so we fit once the car has been moved off the motorway. If the road has no hard shoulder, see our guide to a flat tyre on a smart motorway.

Will sidewall damage fail an MOT?

Serious sidewall damage fails; a cosmetic scuff does not. The MOT inspection manual sets two categories for it:

• Major: a cut over 25mm or 10% of the section width, whichever is greater, deep enough to reach the ply or cords.
• Dangerous: a lump, bulge or tear caused by separation or partial failure of the tyre's structure, including any lifting of the tread rubber, or cords that are exposed or damaged.

Under the manual's defect categories, a car with any Major or Dangerous defect fails. Some sites say sidewall damage is an automatic fail; the manual does not say that, and a scuff in the rubber is not on its list of defects.

Is sidewall damage legal in the UK?

Cosmetic scuffs are legal. Regulation 27 of the Road Vehicles (Construction and Use) Regulations 1986 makes it an offence to use a tyre on the road that has:

• a cut over 25mm or 10% of the section width, whichever is greater, measured in any direction on the outside of the tyre and deep enough to reach the ply or cord;
• any lump, bulge or tear caused by separation or partial failure of its structure;
• any of the ply or cord exposed.

The same regulation also requires a tyre to be fit for the use the vehicle is being put to, and the Highway Code says tyres should be free from certain cuts and other defects.

Can you get points for sidewall damage?

Yes: up to £2,500 for a car in England and Wales, and 3 penalty points under endorsement code CU30 for using a vehicle with defective tyres. The £2,500 comes from two Acts. The Road Traffic Offenders Act 1988 puts the offence at level 4 on the standard scale for a car, and the Sentencing Act 2020 sets level 4 at £2,500. TyreSafe notes that the fine can apply to each defective tyre. Our guide to UK tyre laws and fines covers tread depth and the other rules.

Tyre kerb damage: check the alloy too

Kerb damage often comes from everyday, low-speed moments: parking, a tight turn, a swerve. TyreSafe notes that kerbs and potholes can damage both the sidewall and the wheel rim. So when you look at the tyre, look at the wheel as well:

• A crack in the rim or a spoke. The MOT manual lists any fracture in a wheel as a Dangerous defect. Do not drive on it.
• A bent lip. A badly distorted wheel is a Major defect. If the tyre keeps losing pressure after the knock, have the rim checked as well as the tyre.
• A gouged rim edge. A fitter checks the rim edge for sharp burrs before fitting, because a burr can cut into a new tyre.
• A tyre that looks off its seat. A tyre not seated properly on the rim is also a Major defect.

A bulge may not be obvious straight after the knock, so look again a day or two later and keep an eye on the pressure. Cosmetic scrapes on the alloy are a job for a wheel refurbisher, not a tyre fitter. Our guide to a kerbed alloy wheel explains when the wheel itself is unsafe. If a fitter finds the rim cracked or badly bent, they should tell you before fitting anything to it.

Bulges, cracking and other causes

If you have found a bulge in the sidewall, that guide covers it in full. In short, Michelin explains that a bubble on the sidewall means the carcass ply behind the rubber has been punctured after hitting a kerb or pothole, and that the tyre cannot be repaired.

Cracking is a judgement call, and no standard gives drivers a depth to measure. The BTMA summary only says cracking that reaches the casing cannot be repaired; Michelin treats sidewall cracks as a sign of ageing. Fine crazing on an older tyre is a reason to have it looked at, and the date code on the sidewall tells you how old the tyre is.

Pressure is the cause you control. The Highway Code says to check pressures weekly, before a journey, with the tyres cold. TyreSafe advises inspecting tyres at least monthly for cuts, bulges and cracking.

A nail or screw in the sidewall

A nail in the tyre sidewall is treated like a cut: it is outside area T, so the tyre is replaced, and TyreSafe says a repair is not possible when a puncture has caused damage close to or on the sidewall. A nail in the middle of the tread is often a different story, so if you are not sure exactly where it sits, our nail in tyre guide shows where the line falls. Leave the nail in until a fitter has looked at it.

Run-flat tyres with sidewall damage

Run-flats have stiffer sidewalls, but sidewall damage still means a new tyre. Regulation 27 has a narrow exception that lets a marked run-flat type tyre be used while deflated. TyreSafe says run-flats are designed to get you to your destination, for up to 50 miles at a maximum of 50mph. It adds that a run-flat driven deflated is unsafe to repair. The regulation 27 exception lasts only while the tyre is deflated: once it is reinflated, or the run-flat range is used up, the normal cut, bulge and exposed-cord rules apply again.

Do you need to replace one tyre or two?

Only the damaged tyre has to be replaced by law; regulation 27 has no rule about pairs. TyreSafe advises replacing tyres in pairs. A common trade rule of thumb is that the tread gap decides it: if the other tyre on the axle is nearly new, one new tyre is usually enough. If it is well worn, a pair keeps grip even side to side, which matters most when braking in the wet. Our guide to replacing two or four tyres goes into the detail.

Need someone to come to you?

If the damage has reached the cords, the useful question is how to get a new tyre on without driving on the damaged one. We bring a new tyre and fit it where the car is parked, at home, at work or somewhere safe off the main road: a replacement tyre fitted where the car is parked, with no need to drive on the damaged one. We typically arrive 30 to 60 minutes after you call, the fitting takes 20 to 30 minutes, and we balance the wheel on the van. There is no out-of-hours surcharge. The cost is quoted on the phone before anyone sets off.

• Need it done today? We source the tyre and fit it the same day.
• Stuck at night or at a weekend? The 24/7 emergency tyre call-out covers it.

We fit cars, SUVs, 4x4s, EVs and vans, we are fully insured, and new tyres carry a 2-year warranty.

Sources

Checked on 2 October 2026. The legal, MOT and repair points in this guide come from these sources; the fitter's checks describe how the job is generally done in the trade. The repair rules come from the BTMA's published summary of BS AU 159; the full standard is not free to read, and we could not confirm whether a later edition changed them.

• The Road Vehicles (Construction and Use) Regulations 1986, regulation 27 (legislation.gov.uk)
• MOT inspection manual, section 5: axles, wheels, tyres and suspension (DVSA)
• MOT inspection manual: introduction and defect categories (DVSA)
• Endorsement codes and penalty points (GOV.UK)
• Road Traffic Offenders Act 1988, Schedule 2 and Sentencing Act 2020, section 122 (legislation.gov.uk)
• The Highway Code, Annex 6 and rules 274 to 287 (GOV.UK)
• Breakdowns (National Highways)
• Minor repairs to passenger car and light van tyres (British Tyre Manufacturers' Association summary of BS AU 159)
• TyreSafe: Tyres and the law, Punctures and puncture repairs, Tyre repair and spares, Car tyre safety
• Tyre sidewall damage: what should you do? (Michelin UK)

Photos: hero by Erik Mclean on Pexels. Kerb gouge: Cut in the tire by Bearas, CC BY-SA 4.0. Deep cut: Kaputter Reifen Toyota 3 by Thirunavukkarasye-Raveendran, CC BY 4.0. Bulge: Tire bubble by Osnetwork, CC BY-SA 3.0. The three damage photos are cropped and resized from the originals; the crops of the CC BY-SA photos are shared under the same licence.

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