AKRON-North America's largest independent commercial dealers, who sell and service more steel-radial truck tires than anybody, are acutely aware of sidewall zipper problems in such tires. Nineteen out of 20 dealers who answered the question concerning zipper failures posed by TIRE BUSINESS on its commercial dealership survey, said they have experienced at least one of these potentially explosive sidewall ruptures.
``Zippers,'' which occur when the tire's radial steel cords become weakened and break, are the subject of a study by an industry task force organized by the American Retreaders' Association.
Some survey respondents, such as Jerry Bauer, president of Durand, Wis.-based Bauer Built Inc., and a past president of the National Tire Dealers & Retreaders Association, and James J. Seiter, president of Fort Smith, Ark.-based Treadco Inc., called zippering a serious and increasing problem.
On the other hand, several dealers, such as Tom Freedman, CFO for Les Schwab Tire Centers Inc. in Prineville, Ore., and Brent Hesje, marketing manager for Fountain Tire in Edmonton, Alberta, described the zipper problem as ``minimal.'' And James Parkhouse, of Parkhouse Tire Inc. in Bell Gardens, Calif., said his dealership has never experienced that type of failure.
Meanwhile, two dealers responding to the survey said they have found ways to reduce or alleviate the problem.
John Perdue, president of Perdue Tire Inc., in Newark, Calif., said his employees are well aware of the problem and are getting better at detecting potential zippers before they occur.
Employees of the company carefully follow recommended procedures for inspecting and handling steel radials, including airing up the tires in safety cages, inflating to 35 psi and waiting for the development of sidewall bulges and always being on the alert for the ``snap, crackle and pop'' of breaking cords, he said.
As a result, the Perdue Tire staff has been able to detect about a dozen zippers in the making over the past six months, according to Mr. Perdue.
Meanwhile, Thomas M. Duff, president of Southern Tire Mart Inc. in Columbia, Miss., said his company has ``implemented proper retreading, repair and inflation procedures'' that have ``virtually eliminated'' the problem of encountering zipper blowouts at his locations.
Contacted by telephone and asked to elaborate, Mr. Duff said Southern Tire Mart has been looking into the zippering phenomenon for about two years with the help of the company's tire and retreading suppliers.
What the dealership learned, he said, was that most zipper ruptures it investigated were the result of internal cord damage caused by underinflation or overloading-a situation made worse when the tire's user fails to mark it for special attention.
In an effort to correct this problem, Southern Tire Mart asked its commercial customers to identify tires that had been repaired or run with low inflation pressure.
Now, as those tires arrive at the dealership for service, workers give them extra care and attention during inspection and processing.
Most truck owners, he said, gladly comply with the company's request, since they, too, are concerned about the liabilities posed by zipper explosions. Tires sent to dealerships by accounts known to have chronic underinflation automatically are tagged.
As a result, Mr. Duff said, Southern Tire Mart's five Bandag plants, which retread nearly 700 truck tires per day, haven't experienced a zipper rupture in more than a year. By comparison, he said, ``we probably would have had 12-13 two years ago.''
Mr. Duff took exception to previously published comments by dealers and retreaders who suggested zipper failures are the fault of manufacturers who aren't interested in correcting the situation.
``I have found that to be totally incorrect,'' said Mr. Duff, explaining representatives of each of his primary tire suppliers, Michelin, Goodyear and Bridgestone, have visited the company during the last two years to help solve its zippering problems.
Moreover, it's unrealistic for dealers to expect manufacturers to build a tire that can't zipper, he contends. ``That's like (asking for) a tire that will never go flat or a tread that will never have irregular wear,'' Mr. Duff said.