Your tyres are the only part of your vehicle that actually touches the road. Everything else — your brakes, your steering, your suspension — depends on four small contact patches, each roughly the size of a hand, to keep you safe. When those tyres are worn or damaged, your safety margin disappears fast.

At Tech & Tyres in Melksham, we see the full spectrum — from tyres that are clearly overdue for replacement, to drivers who didn't realise there was a problem at all. This guide covers everything you need to know.

1. Tread Depth: The Legal Limit and the Safety Limit

In the UK, the legal minimum tread depth for car tyres is 1.6mm across the central three-quarters of the tyre width, around the full circumference. Fall below this and you risk a fine of up to £2,500 and three penalty points — per tyre.

But here's what many drivers don't realise: the safety threshold is higher than the legal one. Most tyre manufacturers and road safety organisations recommend replacing tyres at 3mm, because stopping distances increase dramatically as tread depth falls below that point.

"At 1.6mm tread in wet conditions, stopping distances can be up to 44% longer than at 3mm. On the A350 near Melksham, that's the difference between a near miss and a collision."

How to check: Most tyres have tread wear indicators (TWIs) — small raised bumps in the tread grooves. When the tread is level with these indicators, you're at the legal limit. You can also use a 20p coin: insert it into the tread groove. If the outer band of the coin is visible, your tread is below 3mm.

2. Bulges and Sidewall Damage

A bulge in your tyre sidewall is a structural failure. It means the internal cords that give the tyre its strength have broken, and the outer rubber is the only thing holding the air in. This can fail suddenly — often at speed.

Bulges are commonly caused by:

  • Hitting a pothole at speed
  • Mounting a kerb too fast
  • Running a tyre underinflated

If you spot a bulge, do not drive on that tyre. Replace it immediately. This is non-negotiable.

3. Cracking and Crazing

As tyres age, the rubber compounds dry out and begin to crack. You'll see this as fine lines or crazing on the sidewall and in the tread grooves. This is called dry rot, and it's a particular concern for vehicles that are used infrequently or stored outside.

Even if a tyre has plenty of tread depth, significant cracking can mean it's structurally compromised. UK guidance recommends replacing tyres over 10 years old regardless of apparent condition — and many manufacturers say five to six years for a tyre in regular use.

4. Uneven Wear Patterns

How your tyre wears tells a story. Even wear across the full width is what you want. Anything else is a signal:

  • Wear on the outer or inner edges only: Usually a wheel alignment issue. The tyre is running at an angle. Fix the alignment and replace the tyre.
  • Centre wear only: The tyre has been chronically overinflated. Check pressures and replace.
  • Flat spots: Often caused by locking up under heavy braking. The flat contact with the road grinds away the rubber unevenly.
  • Scalloping or cupping: A wavy wear pattern, usually indicating worn shock absorbers or suspension components.

Uneven wear doesn't just mean you need a new tyre — it usually means there's an underlying issue causing it. Address the root cause, or the new tyre will wear the same way.

5. Vibration and Handling Changes

If your steering wheel vibrates at certain speeds, or your car pulls to one side, don't automatically assume it's a suspension problem. A deformed or damaged tyre can cause the same symptoms. Have the tyres checked first — it's usually the simpler (and cheaper) fix.

6. Age Alone

Even if a tyre looks fine, age matters. The rubber degrades from the inside out, and a tyre that's sat in your garage for seven years may look perfectly usable but have significantly reduced grip and flexibility.

Check the DOT code on the tyre sidewall. The last four digits tell you the week and year of manufacture — for example, "2319" means the 23rd week of 2019. If your tyres were made more than five or six years ago, have them professionally assessed.

Not Sure About Your Tyres?

We offer a free tyre check at our Melksham depot — or we can assess them at your home or workplace. Call us and we'll tell you honestly what needs doing.

Call 07837 637217

What to Do When You Need New Tyres

If you're in Wiltshire, you don't need to book a garage appointment and wait in a reception area. Tech & Tyres fits new tyres at your home, workplace, or roadside — usually same day or next day.

We carry a range of tyres from budget to premium and will always advise you honestly on which option suits your vehicle and driving style. Our mobile fitting equipment meets the same standard as any fixed garage.

Call 07837 637217 for an instant quote, or send us an enquiry and we'll get back to you within two hours.