Cracked or Perished Tyres: The Complete UK Safety Guide
Rubber perishes. It is not a question of if, but when. The real question is whether the cracking on your tyre is a cosmetic nuisance or a structural failure waiting to happen. This guide cuts through the guesswork. You will learn exactly what those cracks mean, how to inspect them properly, when to replace a tyre, and what the MOT and DVSA expect. We will also cover the causes of tyre ageing, manufacturer recommendations, and practical steps to keep your vehicle safe.
If you are unsure about any tyre on your car, caravan, or trailer,
book a professional inspection with TMA Mobile Tyres. We come to you anywhere in Bolton and the surrounding areas.
What Does Tyre Cracking Actually Mean?
Modern tyres are complex engineering products. The rubber compound contains oils and waxes that keep it flexible. Over time, exposure to ultraviolet light, atmospheric ozone, temperature changes, and simple ageing cause these protective agents to break down. The rubber dries out, hardens, and loses its ability to flex without splitting.
This deterioration manifests as cracking. The severity and location of the cracks determine whether the tyre is still safe or needs immediate replacement.
Types of Cracking and What They Mean
| Crack Type |
Appearance |
Severity |
Recommended Action |
| Surface crazing |
Fine, shallow web of lines on the sidewall or tread |
Low (cosmetic) |
Monitor closely, plan for inspection |
| Edge cracking |
Cracks along the outer edge of the tread |
Moderate |
Inspect for depth; often linked to underinflation |
| Sidewall cracking |
Deeper lines or splits on the sidewall face |
High |
Replace immediately if deep or extensive |
| Bead cracking |
Cracks near the rim where the tyre seats |
Critical |
Replace immediately – risk of sudden air loss |
Warning: Cracking accompanied by a bulge or distortion is a red flag. It indicates internal structural failure. Do not drive on the tyre. Arrange immediate replacement.
When Do Cracked Tyres Need Replacing? A Decision Guide
The MOT inspection manual sets clear criteria for tyre condition. However, passing an MOT on a given day is not a guarantee of safety for the rest of the year. Tyre condition can deteriorate rapidly, especially under load or at high speed.
Use this table to assess the severity of cracking on your tyres.
| Finding or Factor |
What It Means |
Practical Response |
| Fine surface crazing only |
Early-stage ageing; structure likely intact |
Arrange a professional inspection and monitor regularly |
| Deep crack that opens when you flex the tyre |
Possible casing exposure; structural integrity may be compromised |
Replace after a competent assessment |
| Cords or ply are visible |
Structural layers are exposed |
Do not drive. Replace immediately |
| Cracking plus a bulge or distortion |
Internal structural failure |
Urgent replacement. Do not drive |
| Cracking on the inward-facing sidewall |
Often missed during routine checks |
Inspect both sidewalls thoroughly |
A tyre with exposed cords is illegal and dangerous. The DVSA considers this a serious defect that will result in an MOT failure and can lead to roadside prohibitions.
How to Inspect Your Tyres for Cracking
Performing a thorough tyre inspection takes only a few minutes but could save your life. Follow this checklist.
Visual Inspection Checklist
- Find the date code. Look for the four-digit DOT code on the sidewall. The last four digits indicate the week and year of manufacture. For example, `2219` means the 22nd week of 2019.
- Inspect both sidewalls. Turn the steering wheel to full lock to see the inner sidewall. Cracking here is often missed.
- Check the tread grooves. Look for cracks at the base of the tread. These can indicate structural weakness.
- Examine the valve area. Cracks around the valve stem can cause slow punctures.
- Look for bulges or distortions. Run your hand over the sidewall to feel for any unevenness.
- Check the other tyres. If one tyre is perishing, the others are likely not far behind.
- Check the spare. Spare tyres age too and should be inspected regularly.
Pro Tip: Do not apply tyre dressing or shine before an inspection. It can mask cracks and make accurate assessment difficult.
What Causes Tyres to Perish and Crack?
Understanding the causes helps you prevent premature ageing.
- Age: Rubber degrades over time regardless of mileage. Most manufacturers recommend replacing tyres at 10 years old, with close inspection from 5 years.
- UV Exposure: Sunlight breaks down the chemical bonds in rubber, leading to cracking.
- Ozone: Atmospheric ozone reacts with rubber, causing fissures.
- Temperature Fluctuations: Repeated heating and cooling cycles accelerate degradation.
- Underinflation: Running tyres with low pressure increases flexing and heat, leading to cracking.
- Storage: Tyres stored outdoors, on caravans, trailers, or second cars, are particularly susceptible.
Can Cracked Tyres Be Repaired?
The short answer is no. Structural cracking cannot be repaired. Glues, dressings, or sealants cannot restore the structural integrity of aged rubber. A puncture in an otherwise sound tyre can be repaired if it meets British Standard BS AU 159. However, if the tyre is cracked or perished, it must be replaced. There is no safe repair for cracked rubber.
Manufacturer Age Recommendations
Different manufacturers offer specific guidance on tyre age. While not legally binding, these recommendations represent best practice.
| Manufacturer |
Age Recommendation |
| Continental |
Replace all tyres over 10 years old |
| Michelin |
Replace tyres 10 years after manufacture |
| Bridgestone |
Replace tyres over 5 years old; definitely replace over 7 years |
| Cooper |
Replace tyres 10 or more years old; do not put tyres over 6 years into service |
These are general guidelines. Always defer to your vehicle manufacturer’s recommendations and the advice of a qualified tyre professional.
What the MOT and DVSA Say About Cracked Tyres
The MOT inspection manual for cars and passenger vehicles sets the legal standards. A tyre with a cut or crack that exposes the cords or ply will fail. Cracking that is deep enough to compromise the tyre’s structure will also result in a failure.
The DVSA has recently updated its guidance, with expanded definitions of unsafe tyre damage and clearer rules on age restrictions. Tyre-related defects are a common cause of roadside prohibitions. An MOT pass on one day does not mean the tyre is safe for the rest of the year.
Myth vs Fact: Cracked Tyres
| Myth |
Fact |
| “Cracked tyres are always illegal.” |
Fine surface crazing may be legal and safe. Deep cracks, exposed cords, or bulges are illegal and dangerous. |
| “Low mileage prevents ageing.” |
No. Rubber degrades through time, UV exposure, and storage conditions, not just use. |
| “A tyre with cracks can be repaired.” |
Structural cracking cannot be repaired. Replacement is the only safe option. |
| “Age alone doesn’t matter.” |
Age is a critical factor. Manufacturers recommend replacement at 5-10 years regardless of tread depth. |
Common Mistakes to Avoid
- Ignoring inner sidewall cracks. These are often missed but are just as dangerous as outer sidewall cracks.
- Applying tyre shine before inspection. This can hide cracks and make assessment difficult.
- Using a tyre repair kit on a cracked tyre. This is unsafe and ineffective. Cracked tyres must be replaced.
- Assuming a tyre with good tread is safe. Tread depth is only one factor. Age and condition are equally important.
- Not checking the spare tyre. Spare tyres age too and can be dangerous if used in an emergency.
Maintenance Advice to Prevent Cracking
- Check tyre pressures monthly. Correct pressure reduces flexing and heat buildup.
- Store tyres properly. Keep them in a cool, dry place away from direct sunlight and ozone sources like electric motors.
- Use a tyre dressing with UV protection. This can help slow degradation, but never apply it before an inspection.
- Inspect tyres regularly. A monthly visual check can catch problems early.
- Replace tyres by age. Follow manufacturer recommendations. Do not wait for cracks to appear.
Emergency Situations: What to Do
If you notice a bulge, deep crack, or exposed cords, do not drive the vehicle. These are signs of imminent tyre failure. A blowout at motorway speeds is extremely dangerous.
If you are already driving and experience a sudden loss of pressure or a blowout:
- Grip the steering wheel firmly.
- Do not brake suddenly. Ease off the accelerator.
- Allow the vehicle to slow down gradually.
- Steer to a safe, flat area away from traffic.
- Call for professional assistance. Do not attempt to fit a spare tyre on the hard shoulder unless it is safe to do so.
For emergency tyre assistance in Bolton and the surrounding areas,
contact TMA Mobile Tyres.
Frequently Asked Questions
Are small cracks on tyres dangerous?
Not necessarily. Fine surface crazing is often cosmetic and does not affect the tyre’s structural integrity. However, any crack that is deep enough to expose the cords or that is accompanied by a bulge is dangerous and requires immediate replacement.
Will cracked tyres fail an MOT?
It depends on the severity. Cracking that exposes the cords or ply will cause a fail. Deep cracking that compromises the tyre’s structure will also fail. Minor surface crazing may not fail but could result in an advisory.
Does tyre age alone mean I need to replace them?
Age alone is not a legal requirement, but it is a critical safety factor. Most manufacturers recommend replacing tyres at 10 years old, with close inspection from 5 years. Tyres aged 10 years or more should be replaced as a precaution.
How do I find the date code on my tyre?
The date code is a four-digit number at the end of the DOT code on the sidewall. The first two digits indicate the week of manufacture, and the last two indicate the year. For example, `2219` means the 22nd week of 2019. The code may be on the inner sidewall, so you may need to turn the steering wheel to see it.
Can cracked tyres be repaired?
No. Structural cracking cannot be repaired. Glues, dressings, or sealants cannot restore the integrity of aged rubber. A tyre with cracks must be replaced.
Does low mileage prevent tyre ageing?
No. Rubber degrades over time due to UV exposure, ozone, and temperature changes, regardless of mileage. A low-mileage car that is parked outdoors can develop cracking just as quickly as a high-mileage car.
What should I check on the other tyres if one is cracked?
If one tyre is showing signs of ageing, the others are likely not far behind. Check all tyres, including the spare, for cracking, bulges, and date codes. Have all tyres assessed by a professional if ageing is widespread.
What causes sidewall cracking?
Sidewall cracking is primarily caused by UV exposure, ozone, and age. Underinflation and long periods of standing can also contribute. Sidewall cracks are particularly dangerous because the sidewall flexes constantly.
Are cracked caravan tyres dangerous?
Yes. Caravan tyres are often left standing for long periods and are exposed to the elements. They age rapidly and can develop dangerous cracking. Caravan tyres should be replaced regularly, irrespective of their visual appearance.
Can I drive with a cracked tyre to a garage?
If the cracking is superficial, you may be able to drive carefully to a nearby garage. However, if the cracks are deep, expose cords, or are accompanied by a bulge, do not drive the vehicle. Arrange for a mobile tyre service to come to you.
How does UV exposure affect tyres?
Ultraviolet radiation from the sun breaks down the chemical bonds in the rubber, leading to hardening and cracking. Vehicles parked outdoors are particularly susceptible.
What is the legal tread depth in the UK?
The legal minimum tread depth for cars and light commercial vehicles is 1.6mm across the central three-quarters of the tread. However, many manufacturers recommend replacing tyres at 3mm for better wet grip.
What is tyre perishing?
Tyre perishing is the deterioration of the rubber compound due to age, UV exposure, ozone, and temperature changes. It manifests as cracking, hardening, and loss of flexibility. Perished tyres are unsafe and should be replaced.
How should I store spare tyres?
Store spare tyres in a cool, dry place away from direct sunlight and sources of ozone. Avoid stacking them without support, as this can cause flat spots or sidewall damage.
Do new tyres have a shelf life?
Yes. Tyres degrade even when not in use. Most manufacturers recommend that tyres over 6 years old should not be put into service. Always check the date code when buying new tyres.
Need a Professional Opinion? We Can Help
Assessing tyre cracking accurately requires experience and a trained eye. A photograph cannot capture the full picture. Depth, location, and the tyre’s history all play a role in determining safety. If you are unsure about any tyre on your vehicle, caravan, or trailer, do not guess.
Send clear photographs of the cracking, the complete sidewall, and the four-digit date code to TMA Mobile Tyres. Explain how the vehicle is stored and whether the other tyres show similar deterioration. We will provide a professional assessment and, if necessary, come to your location in Bolton or the surrounding areas to fit replacements.
Request an ageing-tyre assessment today.
For more information, explore our guides on
tyre sidewall codes and
sidewall damage.
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