Table 2-1.  Unit Level Preventive Maintenance Checks and Services HMMWV (Cont’d). ITEM NO. INTERVAL ITEM TO BE INSPECTED PROCEDURES 17 Semi- Exhaust Inspect for cracked and loose pipes, Cracked, loose, or holes in annually Components    muffler, and hangers. Check for pipes or muffler. Exhaust exhaust leaks. leak. 18 Semi- Frame, a.  Inspect frame side rails for cracks, a.  Any loose or missing annually Support breaks, bends, wear, deterioration, fasteners. Cracks, bends, Braces and missing or loose fasteners. or breaks in frame. and Cross- members b.  Inspect support braces and b.  Any loose or missing crossmembers for cracks, fasteners. Cracks, bends, breaks, bends, deterioration, and or breaks in crossmembers loose or missing fasteners. or support braces. 19 Semi- Tires annually a.  Check tread depth of tires with tire a.  Tread depth is less gauge. If tread depth is less than than 1/16 in. (1.59 mm). 1/16 in.(1.59 mm), replace tire. Radial tires will take approximately 1,300 miles (2,092 km) to wear 1/32 in. (0.79 mm). If mission will require the vehicle to travel this distance within a month, replace tire if it measures 3/32 in. (2.38 mm). TM 9-2320-387-24-1 Change 1 2-19 NOT FULLY MISSION CAPABLE IF: WARNING Changing tire pressures or wheel alignment out of the recommended specification may adversely affect the vehicle’s handling characteristics. Loss of vehicle control may result, causing serious injury or death to personnel and damage to equipment. NOTE Vehicle must be up on jack stands for the following checks.