Checking Tyre Pressure

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What Does a Sidewall Bulge Tell You About Your Car's Tyre?

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If you pride yourself on being a careful motorist, you may walk around your vehicle to inspect it each morning before you head out on the road. You take a close look at your tyres to ensure that you still have enough tread in place and to check for nails or other embedded objects. Yet, what if you come across a strange phenomenon that you've never seen before but that should nevertheless prompt you to pause and consider? What if you can see a pronounced bulge on the sidewall of one of these tyres? What is this, and what should you do?

Signs of Damage

A bulge or bubble on the side of a tyre means that it probably has some internal damage. This means that the frame inside the rubber casing has become distorted or the inner tube has developed a leak.

How Tyres Are Made

Many people do not realise that within the tyre is a separate tube that is connected to the valve. It's not a part of the tyre as such, but is a sealed unit that holds the air during inflation. This separate airbag will entirely fill the space inside the tyre to provide the necessary support.

The tyre itself is made from many individual pieces of rubber that are glued together during the manufacturing process. Everything is built around a metal frame that gives the tyre its inherent shape before the tread belt is added at the end.

The Perils of Under-Inflation

Each of those tyres is designed to operate under certain conditions and with a very precise amount of air inside. It's important to check pressures often, and never a good idea to run with too much or too little within. If the tyre is underinflated, it can also overheat when driving along a motorway, which may eventually lead to internal damage. In some cases, this is what causes a bulge or bubble to form.

Damaging Road Conditions

However, if you are careful to put enough air in each tyre, this damage may have been caused by an object on the road or simply a pothole. If you're unlucky, the tyre could sustain damage when it hits the edge of a pothole at a certain speed and in a specific direction. This could cause the inner tube to burst, and when this happens, the escaping air will create the bubble or bulge on your sidewall.

What to Do Next

Before you drive the vehicle, call your tyre technician and get their advice. It may be safer to change the tyre first and mount the spare, as you will almost certainly have to replace the damaged one. For more information on tyres, contact a professional near you.