23/07/2026
We often talk about how dangerous tire blowouts are, but who has actually summarized the different ways a tire can blow out? Today, Tire Business introduces three types of blowouts: crown blowout, sidewall blowout, and zipper blowout.
1.Crown Blowout
Quality issues can basically be ruled out. From a structural perspective, the crown (the top of the tire) of a radial tire is the strongest part. The sidewall has only one layer of steel cords, while the crown typically has 4 to 6 layers. The vast majority of crown blowouts are caused by external impact.
They usually happen under severe impact, such as hitting a pothole on the highway and suffering a heavy blow. Another cause is when a tire gets punctured and the hole is relatively large. Such a tire should have been discarded, but if it is reluctantly repaired and put back into use, a blowout is very likely to occur.
Also, if a tire has been used for too long and the steel belt layer under the tread has separated, continued use will lead to tread deformation, irregular bulges, and eventually a blowout. Generally, a blowout does not happen all of a sudden — it is a gradual process. Therefore, once a tire reaches its wear limit, it must not be used any longer.
2. Sidewall Blowout
The tire sidewall is the most vulnerable part of the tire and is also where blowouts most commonly occur. So, what are the main causes of a sidewall blowout?
Improper driving, such as mounting a high curb, driving over a road shoulder, going through deep potholes, or running over rocks at high speed, can all cause damage to the tire sidewall — leading to bulging or even a blowout.
When a tire receives an impact, the tread is the first to bear the brunt. However, the tread is quite tough; under normal circumstances, it has at least two layers of steel belts and relatively thick tread rubber. Unless an object is extremely sharp, it cannot damage the tread. The sidewall then takes the second wave of impact.
The sidewall is relatively soft and will deform or fold under the impact. The internal cords of the sidewall may break or develop gaps due to this folding, which then leads to tire bulging and even a blowout.
The tire sidewall is the softest part of the tire. Its function is to cushion impact and transmit kinetic energy. Therefore, a wider sidewall provides better comfort but results in relatively greater loss of kinetic energy transmission; a narrower sidewall enhances sporty driving performance but compromises comfort.
3. Zipper Blowout
This type of blowout refers to a tire rupture in which a zipper-like crack forms circumferentially along the sidewall while the vehicle is traveling at high speed. This form of tire damage is extremely hazardous to driving safety. So, what are the causes of a zipper blowout?
1) Overload-induced tensile breakage of steel cords — that is, when the tire carries an excessive load and the inflation pressure is too high, the stress on the carcass steel cords becomes excessive, causing them to break.
2) Steel cord flex fatigue breakage — this is related to the tire's usage conditions. When the tire is under-inflated, repeated braking and cornering can cause fatigue breakage of the steel cords, and the rubber is also prone to separating from the steel cords.
3) Steel cord abrasion leading to overload tensile breakage, which causes a blowout.
