Document Sample
					                                         COMMERCIAL FLEET
                                            TIRE DIGEST
                                         The authoritative guide to reducing commercial tire expenditures from
                                                            Pressure Systems International,
                                            the manufacturer of the Meritor Tire Inflation System by PSIΤΜ

                             VOLUME 1 ISSUE 11                                                              OCTOBER 2007

                             Preventing Tire Sidewall (Zipper) Rupture
                             We all know how important it is to main-        rupture.
                             tain proper tire inflation pressure to:
                                                                             Caution is required during the inflation proc-
                             •   Maximize fuel economy                       ess.
                             •   Maximize tire removal mileage               If a tire is going to zipper, it will occur when
                                                                             the tire is remounted and inflated before go-
                             •   Minimize irregular tire wear
                                                                             ing back into service, either as a new tire
                             •   Maximize retreadability                     that had a puncture repair or as a new re-
                             •   Reduce roadside service calls               tread.
                             But a potentially dangerous condition           A safety cage is absolutely required when
   Courtesy of the TMC       can develop when radial tires run with          inflating a truck tire.
     Radial Tire Wear        little or no air for an extended period of      If a zipper rupture occurs, you want it to
 Conditions Analysis Guide
                             time. This condition is technically called      happen inside the cage, otherwise people can
                             a circumferential upper sidewall rupture.       be injured. As an added precaution, tires
 MTIS™ will be               The more common name is a “zipper               should be 20% overinflated inside the safety
 featured at the             break” or “zipper rupture”.                     cage to insure that if the tire is going to rup-
  ArvinMeritor                                                               ture, it will do so INSIDE the cage.
                             To understand this condition, think of
  Booth (#104)               the individual steel wires running
                             through the sidewall as “paper clips”.          The Rubber Manufacturers Association pub-
   at the IANA                                                               lishes a wall chart that explains the proper
                             When a tire is running the recommended
Intermodal Expo              pressure, those wires are in tension. But       procedure when inflating tires along with the
   being held                if a tire runs significantly under inflated     procedure for checking tires for possible zip-
November 10-13               (with little or no air) for an extended         pers. Contact the RMA at to
                             period of time those wires or “paper            order your wall charts. Or you can call the
 at the Georgia                                                              RMA at 800-325-5005 X-242 and order: Pub-
                             clips” are no longer in tension. In this
 World Congress              condition, the tire sidewall will flex sig-     lication 33#2 23/95 “Inspection Procedures
    Center in                nificantly more than normal as the tire         for Identification of Potential Zipper Ruptures
     Atlanta.                now rotates underinflated and over-             in Steel Cord Radial Medium & Light Truck
                             loaded. What happens if you keep bend-          Tires plus Wall Chart”.
                             ing a paper clip?       It will eventually      Remember air inside the tire is what carries
Visit us On-line             break. The same analogy holds true              the load
                             here. The sidewall wires will continue to
For current and back         weaken as the tire runs with little or no       •   Running underinflated with little or no air
                             air (inside duals are especially prone to       for an extended period of time will cause se-
      issues of
                             this condition).                                vere sidewall deflection, generate a high
Commercial Fleet                                                             amount of heat, and the sidewall wires may
                             After the retread process is when extra         become weakened.
  Tire Digest
                             caution is required.
                                                                             • To prevent possible zipper ruptures oc-
                             It is very difficult to determine if a radial
 And to subscribe or                                                         curring when a tire is put back into service
                             truck tire ran with little or no air for an
     submit your                                                             because of a puncture or as a retread, al-
                             extended period of time. Even if the tire
    inquiries to be                                                          ways inflate the tire in a safety cage and fol-
                             is inspected before and after retreading,
 answered here, go to                                                        low all safety precautions.
                             there is no guarantee that the technician
                             can determine if the tire ran significantly     • Using automatic tire inflation systems to
      www.                   underinflated for a long period of time.        insure that your tires are always running at
  psitiredigest              Tires that have those weakened wires in         recommended tire inflation pressure is one
                                                                             approach to significantly reducing zipper rup-
      .com                   the sidewall are the suspect tires that
                                                                             tures from occurring at your fleet.
                             have the potential to experience a zipper