When Should You Replace Your Tyres?

Our lives depend on the condition of our tyres, and yet they're one of the most overlooked parts of the car. We put together a guide on what to look out for and when to know for sure that it's time to replace them.
Jason Snyman
2018-08-14

We often neglect the tyres on our vehicle, but we really shouldn’t. When you think about it, our lives depend on them. They’re all that stands in the way between the road passing beneath us and the vehicle we’re sitting in. They take an absolute beating each and every time we get in and go for a drive, so it’s in our best interest to keep up with any necessary maintenance.

We’ve written a little bit about what happens when your tyres fail you while driving – and the results are horrifying. You could lose control of your vehicle, flip your car over, or at the very least, become stranded in the middle of nowhere. With the right maintenance, these nightmarish scenarios could be avoided.

According to the US Tire Manufacturers Association (USTMA), 35% of American motorists can’t tell when their tyres are bald. Furthermore, 40% think they can tell if a tyre is under-inflated just by looking at it – must be some kind of superpower – and only 17% know how to check their tyre pressure. Also, they spelt tyre completely wrong.

So! We’re going to help you avoid embarrassment. You need to know what to look for when inspecting your car – especially the state of your tyres. This way, you can replace them before something goes wrong.

It has been said that you could tell a lot about the way a person drives by just glancing at the condition of their tyres. Bad driving inevitably leads to savage wear and tear. But, a cold fact of life is that just as the soles of our sneakers wear over time, so do our wheels. And there’s very little you can do about it.

With use over time, the state of the roads or exposure to the elements – all tyres will eventually need replacing.

In this article, we’ll go through everything you need to know about tyre upkeep. What are the warning signs you should keep an eye out for, and when do you need to replace them?
 

Check Your Tread Depth

This is one of the most obvious warning signs – worn tread. The problem is that so few of us ever really get down there to inspect it.

Obviously, it gets a little tricky when it comes to measuring how much tread you have left. In the past, people would have to use a tread depth meter or some other trick to gauge the depth.

Thankfully, many modern tyres now have a marker built right in to let you know when the tread has worn too far. It’s called a Tread Wear Indicator, and you can locate them by finding a small triangle shape marked TWI on the shoulder of the tyre. The triangle points toward the TWI.

The Indicator is a raised section about 1.6mm high, found running across the middle of the tread inside the grooves. So, when the actual tread has worn down to the point when it is level with the TWI – then you know that you only have 1.6mm of tread left, and you need to replace the tyre.
 

The more worn your tread is, the less grip you’ll have on the road, especially in wet weather. It’s also worth mentioning that if your tread is worn to less than 1.6mm, it technically means that your car is no longer roadworthy. This is according to the National Road Traffic Act. So, not only is it illegal to drive your vehicle under these conditions, but it also means that when you’re involved in a car accident – your car insurance probably won’t pay out any of your claims. If your tyres don’t have a TWI – 1mm is the legal limit. Of course, it’s advisable to change your tyres way before this point. Anything less than 3mm of tread drastically reduces handling and control.

Cracks In The Sidewall Of The Tyre

While worn tread may be the most common problem motorists experience – there is another which is often overlooked. Cracks in the sidewall, caused by wear and exposure to the sun, are easier to spot than bad tread – and when you do they can be quite alarming.

With good cause.

While usually a sign that the tyre has developed a leak, tyres in this condition could blow out at any moment. The exposure to UV has broken down the oils and chemicals and turned the rubber brittle. The sidewall could eventually collapse, the tread could separate from the rest of the wheel, etc.

It’s a major concern, and something you definitely want to avoid. Don’t ignore it, or forget about it, or hope for the best, because the cracks will get worse and worse with use.

A good sign that you may have a bad crack or puncture is when the tyre makes a whining or squeaking noise as the air compression changes. Of course, strange noises never mean anything good.

By performing a visual check every week, you can look for any cuts, gashes, grooves or cracks in the side of the tyre. If you spot any, keep a sharp eye on them and see to the repairs or replacement as soon as possible.
 

Bulges, Blisters and Bubbles

These aren’t friendly at all. When the outer surface of a tyre begins to weaken, we sometimes see bulges emerge – extending outward from the surface like a haematoma after a nasty fall.
 

If we’re sticking with comparisons to the human body – think of it as an aneurysm. Before you completely blow an artery, you’ll need to get medical attention as soon as possible.

It’s the same thing with your tyres. These problems could very easily cause a blow-out while driving, and that’s something you really want to avoid for the rest of your life. They’re usually caused by one of two reasons:

  • The uneven weakening of a tyre’s outer surface could lead to bulges, because the pressure inside the tyre pushes out the weakened area.
  • The rigid internal frame of the tyre could have been damaged. This would allow air pressure to get into the more flexible outer layers of the tyre. The damage to the frame is commonly caused by hitting pavements or potholes, or driving with low tyre pressure.

So, when you notice bulges, it means that the structural integrity of the tyre has been compromised. These things happen – even to brand new tyres – and it’s better to just take the car in to a service centre as soon as possible. And make a point of driving very, very carefully.
 

(Not So) Good Vibrations

After a while, everybody gets used to the feeling of their car. You know the rev count, you know the handling and you know the sound of the engine. So, surely, you’d also know when something doesn’t feel right.

Vibration is one of these things – unavoidable when driving anywhere – but there’s a certain kind of excessive vibration which alerts the driver to trouble. There could be any number of reasons for it. 

  • Your shock absorbers / suspension may have some problems;
  • One, or more, of the wheels might be bent or damaged. This will cause them to spin in an imperfect circle;
  • Your wheel alignment could be off. Poor alignment will cause your tyres to wear unevenly;
  • Internal damage will also lead to irregular spinning, despite the appearance of the wheel being fine.

Most annoying of all is that even if your tyres are fine, that vibration could do a fair amount of damage to them in the long run. Then you’ll have a whole bunch of problems. So, when you’re driving down a fairly good road and your car starts shaking as if you were off-roading through the Karoo – take it in and have it looked at.
 

Tyres

All tyres wear out or become damaged and will eventually need to be replaced. How quickly this wear and tear happens depends on a large variety of things. Maintaining them, and driving properly, certainly won’t hurt.

Your vehicle’s braking, steering and handling are just some of the things affected by bald, misaligned or damaged wheels.

Fuel efficiency, believe it or not, is also affected by your tyre pressure. This pressure should be checked at least every two weeks. The correct pressure amount can be found on a placard attached to the body of the car – usually on the inside of the driver’s door – or in the owner’s manual.

And, of course, the smoother the tread is, the harder it will be to stop in an emergency or control your car in the rain.
 

Again, all tyres have an expiration date. Even the spare tyre – just sitting there in your boot – will deteriorate over time. The rubber will weaken. So, a safe bet is to replace it every 6 – 10 years, depending on the use.

Many people who live in areas prone to snowfall even invest in winter tyres – specially designed for that kind of weather – and regularly rotate them depending on the season. Rotating your tyres, in general, will help you get the most out of them. They wear at different rates depending on their position on the car. So, rotating them around the car will ensure that the wear will be evenly distributed.

When buying new tyres, it’s important to buy them in pairs, and make sure they’re all the same size.