How did I end up with this bulge on my tyre?
In fact there are several things which can damage the tyre structure, resulting in a bulge and potentially a blowout. These include (among others) catching your tyre on a kerb, hitting a pothole or an object on the road, as well as chronic under-inflation.
This type of impact can damage the textile cords that make up the structure of the tyre, allowing a bulge or bubble to form on the sidewall. At first, you probably won’t notice any air loss, but if you continue driving on the deformed tyre, this will lead to premature tyre wear, which will eventually result in a blowout.
Unlike certain punctures, a sidewall bulge cannot be repaired and you must replace the damaged tyre as soon as possible.