Knowing when to replace your tyres can feel confusing. Your mate at work says his tyres are fine with minimal tread, the garage says you need new ones, and online advice seems contradictory. Let’s cut through the confusion with clear, practical guidance on when your tyres actually need replacing.
The 1.6mm Rule and Why It’s Not Enough
UK law requires a minimum tread depth of 1.6mm, but this doesn’t mean you should wait until you hit this limit. By the time you’re at the legal minimum, your tyres have already lost significant performance.
Tests show that stopping distances in wet conditions increase by up to 50% when tread depth drops from 3mm to 1.6mm. That’s the difference between stopping safely and rear-ending the car in front.
Think of 3mm as your action point, not 1.6mm. When your tyres reach 3mm, start planning for replacement. This gives you time to shop around and choose quality tyres rather than making an emergency purchase when you fail an MOT.
Using the 20p Test Correctly
The 20p coin test is widely known but often misunderstood. Insert a 20p coin into the main tread grooves of your tyre. If the outer band of the coin is visible, your tread is below the legal 1.6mm limit.
However, don’t just check one spot. Tyres wear unevenly, so test multiple points around the tyre and across its width. Pay particular attention to the inner and outer edges, where wear often occurs first due to alignment issues.
Check all four tyres, including the spare if you have one. You might be surprised to find significant variation between them.
Understanding Uneven Wear Patterns
How your tyres wear tells you a lot about your vehicle’s health. Uneven wear isn’t just about replacing tyres sooner than expected. It indicates underlying issues that will destroy your new tyres just as quickly if not addressed.
Centre wear suggests over-inflation. You’re running your tyres too hard, reducing their contact patch and wearing out the middle faster than the edges. Check your pressures and reduce them to the manufacturer’s recommendation.
Edge wear indicates under-inflation. The tyre is flexing too much, causing the shoulders to wear faster. This also increases fuel consumption and makes the tyre run hotter, raising the risk of failure.
If one edge is wearing faster than the other, your wheel alignment is off. This needs correcting before fitting new tyres, or you’ll simply repeat the problem. A professional alignment check is always worthwhile when replacing tyres.
Bulges and Sidewall Damage
Bulges on your tyre sidewall are not wear issues but they’re an immediate replace-right-now situation. A bulge indicates the internal structure has failed. The tyre could blow out at any moment, particularly at motorway speeds.
Never drive on a bulged tyre, not even to the garage. If you spot a bulge during your morning check, that’s a call for mobile tyre fitting, not a cautious drive to the nearest garage.
Sidewall cuts are equally serious. Small scuffs from kerbs are usually fine, but any cut that’s deep or shows the internal cords requires immediate replacement. The sidewall is under enormous stress and any weakness can lead to catastrophic failure.
When Cracks Appear
As tyres age, small cracks start appearing in the rubber. Light surface crazing might be cosmetic, but deeper cracks in the tread or between the tread blocks indicate the rubber is degrading.
Check the sidewalls carefully. Cracks here are more serious than in the tread because the sidewall flexes constantly while driving. If you can see fabric or cording through any crack, replace the tyre immediately.
Cracking accelerates with age and exposure to sunlight. If your car sits outside all year, your tyres will age faster than those on a garaged vehicle.
The Six-Year Rule
Tyres degrade chemically over time, regardless of mileage or tread depth. Most manufacturers recommend replacing tyres after six years, and some suggest ten years as an absolute maximum under ideal storage conditions.
For a car in regular use in the UK, six years is a sensible replacement point even if the tread looks adequate. The rubber compounds that provide grip in wet weather deteriorate with age, hardening and losing their effectiveness.
You can check your tyre’s age by looking for the DOT code on the sidewall. The last four digits show the week and year of manufacture. For example, 1521 means the 15th week of 2021.
Vibration and Noise as Warning Signs
If your car has developed a vibration that wasn’t there before, especially at certain speeds, it could indicate tyre issues. Bulges, separated treads, or internal damage can all cause vibration.
Increased road noise is another warning sign. If your tyres have suddenly become noisier, they may be wearing unevenly or the tread pattern may be damaged. While some noise increase is normal as tyres wear, a sudden change deserves investigation.
Don’t ignore these symptoms. They often indicate problems that will get worse, potentially leading to tyre failure or affecting other vehicle components.
Punctures and Repairs
Not every puncture means replacing the tyre, but there are limits to what can be safely repaired. Punctures in the central three-quarters of the tread, caused by objects up to 6mm in diameter, can usually be repaired from the inside using a proper patch and plug combination.
Sidewall punctures cannot be safely repaired. The sidewall flexes too much for a repair to hold reliably. Similarly, punctures in the shoulder area (the transition from tread to sidewall) are generally not repairable.
If a tyre has been driven on while flat, the internal structure may be damaged beyond repair even if the puncture itself is in a repairable location. Always get professional assessment rather than assuming a puncture can be fixed.
Seasonal Change Considerations
If you run separate summer and winter tyres or switch to all-season tyres, assess the condition of your stored set before refitting them. Don’t assume they’re fine just because they’ve been in your garage for six months.
Check for cracks, bulges, or deterioration that may have occurred during storage. Verify the tread depth hasn’t dropped below your comfort threshold. Remember, you’re trusting these tyres with your safety for the next season.
Storage conditions matter. Tyres should be kept in a cool, dry place away from direct sunlight, electric motors (which produce ozone that degrades rubber), and chemicals. Standing water or damp conditions accelerate degradation.
The Cost of Waiting Too Long
Delaying tyre replacement to save money often costs more in the long run. Worn tyres reduce fuel efficiency, so you’re spending more on petrol. They increase stopping distances, raising your accident risk. And if they fail an MOT, you’ll need emergency replacement anyway, usually at whatever price you can get quickly.
Budget for tyres as part of your regular vehicle maintenance. Knowing you’ll need new tyres in six months gives you time to find the best deals and choose quality products rather than grabbing whatever’s available in an emergency.
When to Seek Professional Assessment
If you’re unsure about your tyres’ condition, get them checked professionally. Many tyre services, including our mobile service, offer free tyre inspections. We’ll measure the tread depth accurately, check for damage you might have missed, and give you honest advice about whether replacement is needed now or can wait.
For vehicles under heavy use, such as company cars or delivery vehicles, professional inspections every three months help catch problems early and plan replacements efficiently.
Your tyres are too important for guesswork. When in doubt, get them checked. DC Emergency Tyre Fitting provides expert mobile inspections across Barnsley, Doncaster, Rotherham, Sheffield, and Wakefield. We’ll come to you and give you straight answers about what your tyres need.
