The sidewall of a tyre is not always perfectly flat. Sometimes there are small indentations and constrictions. It is important to remember that indentations are harmless and do not affect driving behaviour or safety.
To better understand a constriction, imagine putting a string around an inflated balloon and gently pulling it together. In our example, the balloon is the tyre and the string is the embedded carcass threads that are covered by the rubber. The threads give the tyre its stability and strength and transmit steering and braking forces when driving. During the manufacture of the tyre - or rather during the construction of the carcass, on which the steel belt and then the tread strip are later mounted - there are often one or two overlaps in the carcass. And it is precisely this overlap that is sometimes visible and looks like a constriction after the tyre has been fitted and inflated. If you are still unsure whether it is really just a constriction, you should consult a qualified tyre dealer.