Outside Edge Tyre Wear: Why It Happens and If It’s Legal

Drivers often rely heavily on their vehicles for commuting, school runs, and day-to-day travel. When signs such as uneven tyre wear appear, especially along the outside edge, it can be cause for concern.

Usually, this is caused by common issues, such as under-inflated tyres or even poor alignment. But while it's not automatically illegal, if your tyres are found to be below the legal minimum tread depth of 1.6mm, you could face a fine and even penalty points. Let's take a closer look at why this happens and what drivers can do to prevent it.

What is outside-edge tyre wear?

Understanding outside edge tyre wear helps you spot the signs and adjust your driving habits to prevent it. In most cases, outside edge tyre wear occurs when the outside edge of your tyre looks much more worn — or even smooth — compared to the middle or inside edge of your tyre, which may still have plenty of tread left. If you can see uneven tyre wear patterns, then you may need to change your tyres.

This is very different from even tyre wear, which is what drivers should normally see when their tyres have been properly inflated, aligned, and maintained. If your tyres show even wear, it’s a good sign they’re making consistent contact with the road. This means your car is aligned correctly and can be driven safely. Excessive wear on the outside edge of your tyres means you'll need a new set sooner, and they may be compromising your grip on the road and your braking distances.

Why does tyre wear outside-edge happen?

There are several reasons why you might be experiencing excessive tyre wear on the outside edges of your tyres. Some of the common reasons behind it are related to mechanical issues, poor car maintenance, and even how you've been driving.

Under-inflation

Tyres can wear unevenly due to a lack of air pressure. When this happens, they don't sit evenly on the road surface. This means that the weight of the vehicle is loaded onto the outer edges of the tyres, leading to outside tyre wear.

Misalignment and suspension issues

Drivers can also expect uneven wear on the outside edges of their tyres if their wheels are out of alignment. This also applies to issues with your suspension components. One specific factor is camber, the angle at which the tyres sit relative to the road. If the top of the wheel tilts outward too much (positive camber), it increases pressure on the outside edges, causing them to wear faster.

When misalignment or suspension problems occur, your tyres aren't making even contact with the road. So, the outer edges carry more pressure and wear down more quickly than the centre.

Road conditions and driving habits

Your driving habits can also be a major factor in excessive wear on your outside edges. If you're prone to taking sharp turns, aggressive cornering, or completing high-speed manoeuvres, then you're placing additional strain on the outer edges of your tyres. Other culprits include poor road conditions, such as poorly maintained roads, hitting potholes, and kerbs, all of which can lead to abnormal wear.

How to check your tyres for wear?

It's important to check your tyres for outside tyre wear, as spotting it early can save you money, keep you safe on the road, and also ensure your car is legal to drive. Thankfully, checking for excessive tyre wear is pretty straightforward.

Visual inspections

Simple visual inspections are often all it takes to spot uneven tyre wear. Take a look and compare the tyres' tread pattern across the entire width. If your outside edge looks smoother than the central part of the tyre or inner edge, then there could be uneven wear. Consider doing this at least once a month so you can spot any issues early.

The 20p test

By simply placing a 20p coin into the tyre’s main tread grooves, you'll be able to see if you're within the legal limit. If you can see the outer band of the coin, it means your tread may have worn below the 1.6mm legal minimum, and the tyre could be illegal.

Tread wear indicators

If you have a modern vehicle, it may be fitted with built-in tread wear indicators. These are small, raised bars that are placed within the main grooves of the tyre's tread. As your tyre wears down to the same level as these bars, you'll be given an indication that it might be time for a replacement.

How can you prevent outside-edge wear?

Prevention is better than cure, so here are some steps you can take to prevent uneven tyre wear on the outside edges of your tyres.

Check tyre pressure monthly
Get regular wheel alignment checks
Rotate tyres periodically
Drive sensibly
Avoid overloading your vehicle
Choose higher-quality tyres

When is outside-edge wear illegal?

The legal tyre tread in the UK is 1.6mm across the central three-quarters of the tyre and around the entire circumference. If the outside edge has worn down so far that the tread is below this limit, the tyre is classed as illegal to drive on.

If you’re caught driving with illegal tyres, you could face a fine of up to £2,500 and three penalty points per tyre.

Final thoughts

It's worth remembering that if you've noticed outside tyre wear (but still within the legal limit), then you should take this seriously, even if they're only slightly worn. If you're in doubt about your tyres, their tread, or performance, then consider getting them checked as soon as possible by a local garage or tyre specialist.

FAQs

How do you know when your tyres need to be changed?

If you notice uneven wear, if the tread has fallen below 1.6mm, or if there are visible signs of damage, it may be time to change your tyres.

Do cheaper tyres wear faster?

This is not always the case, but as cheaper tyres often use lower quality rubber, they can wear out faster when compared to higher quality versions, which have been made with durability and performance in mind.

Is outside-edge wear more common on front tyres?

Yes. Outside-edge wear is often more common on front tyres than rear tyres because they handle most of the steering and cornering forces, which puts extra stress on the outside edges.