I noted in an RV forum someone was changing from one brand tire to another brand. One reason given for the brand change was because they had suffered two "zipper" failures with their 22.5" steel body radials. As I do many times when reading RV forums, I posted a link to an earlier post in this blog where I had suggested that a "zipper" failure can occur with any brand steel body radial.
As I try to support my statements with more than just my opinion I dug out an article from Tire Business magazine. In the article it was pointed out that "circumferential fatigue ruptures - known in the trade as 'zippers' in steel radial truck tires" are a failure that can have serious safety consequences and are not just an inconvenience to the RV traveler.
The article goes on to point out that "a zipper rupture is a tire failure in which the tire blows out in the upper sidewall, leaving an even line of broken steel cords exposed, which gives it the appearance of an open zipper. They are typically 10 to 12 inches long but can extend up to 36 inches in length."
The large amount of flexing can occur when a tire is significantly under-inflated. When one tire in a pair of duals looses air it can mean the failure takes longer to become obvious and in the meantime structural damage is being done to the tire that had not lost air but is now being asked to carry up to 100% more load than normal.
What makes this type of failure dangerous is that it is entirely possible for a number of steel body cords to have failed but the rubber in the sidewall has not ruptured at the now low inflation pressure. If that has occurred and the RV owner happens to discover a tire with low pressure then decides to "fix" things by re-inflating the low tire, the damaged tire may now rupture with explosive force when higher pressure air is introduced to the tire.
If you wonder what can happen when a tire explodes a simple Google search of "tire explosion" will return just too many results. Or you can watch this compilation video and ask yourself if you would want to be adding air to any of these tires.
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