The forum on zipper ruptures in all-steel medium and light truck tires held prior to the recent American Retreaders' Association World Tire Conference probably raised more questions than it answered about these types of catastrophic sidewall failures. There was no agreement among tire manufacturers and tire dealers/retreaders about what causes such failures, nor how widespread they really are.
Tire makers generally expressed the opinion that zipper ruptures aren't all that frequent, nor are they caused by faulty tire construction. Rather, said tire makers, zippers result from tire abuse, such as underinflation, overloading or poor repair and maintenance.
Dealers and retreaders, on the other hand, said zipper failures only started showing up five years ago and since have become increasingly common. They suspect this indicates that zippers are the result of some manufacturing change in the steel cord body of radial truck tires.
Despite the lack of consensus, the forum proved a good first step in an industrywide approach to solving a problem that is putting tire service workers and retreaders at risk every time they air up an all-steel radial.
The discussions placed the topic out in the open where a free exchange of ideas can take place and hopefully solve the problem-or at at least minimize the risk.
The forum also resulted in the formation of an industry task force to investigate the causes of zipper explosions and determine what can be done to reduce injuries resulting from them.
The fact is that zipper failures are occurring and people are getting hurt. How many really isn't the issue, although one industry expert, Edward J. Wagner, said he is involved in 18 zipper-explosion court cases.
Until a solution is found, or a simple means of detection developed, dealers and their employees should take extra care when servicing all-steel radial truck tires.
Meanwhile, we commend the ARA for holding the forum. In bringing the industry together, it has jump-started the process of eliminating or at least reducing this dangerous problem.