TM 9-2610-200-14 2-122 SECTION VII.     STORAGE OF TIRES AND TUBES   Paragraph               Page   Number          Paragraph Title             Number 2-52. GENERAL ....................................................................................................              2-122 2-53. STORAGE OF MOUNTED TIRES. ..........................................................              2-122 2-54. STORAGE OF UNMOUNTED TIRES AND TUBES..............................              2-122 2-55. TIRE SHELF LIFE......................................................................................              2-122 2-52.   GENERAL. a.    Factors contributing to deterioration of tires in storage include sunlight, heat, air in motion, ozone, oil, grease, dust and dirt, and water. Ozone is a gas found in the atmosphere that is very harmful to rubber. Tires are specified to contain certain oils and waxes known as antioxidants, which migrate to the surface of the tire when it is flexed in operation. These substances protect the rubber from ozone. When the tire is in storage there is no migration and the tire deteriorates.   b.    Sunlight is especially degrading to tires. Extensive exposure to sunlight can cause severe cracks, rendering the tire unserviceable. It is particularly harmful for those vehicles that remain stationary for lengths of time and are exposed to highly reflective surfaces such as ground covered snow or sand, or heat absorbent surfaces such as black asphalt. (Note, unmounted tires should be stored inside a building. Preferably off the ground in a clean, cool, dry, dark place.).   2-53.   STORAGE OF MOUNTED TIRES. a.    Block up the vehicle in accordance with the applicable vehicle TM. Wrap each tire and wheel assembly with plastic sheet (Item 96, Appendix C). Secure with twine or pressure-sensitive tape. Inspect semiannually to ensure that the cover is in good condition and deterioration has not begun. Tires should not be dormant for more than 60 months.  A schedule for occasional exercise of vehicles and tires in storage, should be established and implement.   b.    For those vehicles exposed to severe sunlight conditions the tires should be protected by blocking out the sun with a barrier. Any means can be employed, as long as it effectively blocks the sun. One way is to use a fabric cover rather than the plastic sheet mention in the preceding paragraph.  Any variety of fabric covers can be designed but as a minimum they should be tailored to cover the outside or exposed side of the tire, and contain a means of securing them such as with twine cord, velcro or elastic. Refer to FM 10-16, General Fabric Repair, for construction guidance and parts.   2-54.   STORAGE OF UNMOUNTED TIRES AND TUBES.   a.    Tires and tubes should be stored in areas that are clean, dry, out of direct sunlight and away from electrical machinery (which emit harmful ozone). For additional information and guidelines relating to the storage of tires and tubes, refer to TM 743-200-1 and applicable vehicle TMs. Unwanted tires or tires and wheel assemblies will be enclosed in polyethylene material NSN 8135-00-579-6487, secured with twine or pressure sensitive tape when stored in sheds or open for periods exceeding 90 days. 2-55.   TIRE SHELF LIFE a.    Even in optimum storage conditions, tires cannot last forever.  Eventually, over time, the tire material will deteriorate which affects the integrity of casing. As such, tires stored at supply points should be issued on a first-in, first-out basis.  Standard tires, which will be used on the highway, should never be stored more than 60 months after date of manufacturer or the last retread or use. Consult the TACOM Item Manager for disposition instructions of any tire not issued and used within 60 months of date of manufacturer, retread or last use.