Scuff  (roughen)  the  area  that  the  patch  will cover, so it will adhere tightly. Apply the proper cement (adhesive), following the directions in the tire repair kit. Remove the covering from the adhesive side of the patch and carefully place it on the inner liner. Using a tool, called a sticher, roll it across the patch to bond the patch tightly to the inner liner. A few basic safety rules for repairing a tubeless tire are as follows: Do  NOT  attempt  to  repair  a  puncture  by plugging  the  tire  from  the  outside.  ALWAYS dismount the tire and patch the inner liner. Do NOT attempt to repair sidewalls or tires with punctures larger than a 1/2 inch. Reduce the air pressure to at least 15-psi, when removing an object from the tire. Broken strands in a steel belted tire can indicate more  serious  damage  than  initially  suspected. Replace the tire. Follow the procedures given in the tire repair kit. TUBE  REPAIR If a tube tire has been punctured but has no other damage,  it  can  be  repaired  with  a  patch.  Remove  the tube from the tire to find the leak. Inflate the tube and then submerge it in water. Bubbles will appear where there is a leak. Mark the spot. Then deflate and dry the tube. There are two methods to patch a tube leak. They are  the  cold-patch  method  and  the  hot-patch  method. With  the  cold-patch  method  (also  known  as  chemical vulcanizing), first make sure the area is clean, dry, and free of grease and oil. Scuff the area around the leak. Then cover the area with vulcanizing cement. Let the cement dry until tacky. Press the patch into place. Roll it from the center out with a "stitching tool" or the edge of the patch kit can. With the hot-patch method, prepare the tube in the same way as for the cold patch. Put the hot patch into place and clamp it. Then, with a match, light the fuel on the  back  of  the  patch.  As  the  fuel  burns,  the  heat vulcanizes  the  patch  to  the  tube.  After  the  patch  has cooled,  inflate  the  tube  and  recheck  for  leaks  by submerging  the  tube  in  water.  Another  kind  of  hot patch  uses  a  vulcanizing  hot  plate.  The  hot  plate supplies the heat required to bond the patch to the tube. PREVENTIVE  MAINTENANCE Preventive  maintenance  of  tires  and  wheels involves   periodic   inspections,   checking   inflation pressure,  wheel  balancing,  and  rotation.  Wheel bearings  are  periodically  lubricated  and  checked  for wear.  These  preventive  maintenance  steps  will  help assure vehicle safety and a longer component life. Rotating Tires Tire  rotation  can  be  beneficial  in  several  ways. When done at the recommended times, it can preserve balanced handling and traction of the tires and even out tire wear. It can even provide performance advantages. Manufacturers  recommend  that  tires  be  rotated  every 3,000 to 5,000 miles, even if they do not show signs of wear.  Tire  rotation  when  done  at  the  recommended times helps even out tire wear by allowing each tire to serve in as many of the wheel positions of the vehicle as possible. NOTE Remember  that  tire  rotation  can  NOT correct  problems  due  to  worn  mechanical  parts or incorrect inflation pressures. While  every  vehicle  is  equipped  with  four  tires, usually  tires  on  the  front  need  to  accomplish  very different  tasks  than  the  rear  tires.  And  the  tasks encountered  on  a  front-wheel  drive  vehicle  are considerably  different  than  those  of  a  rear-wheel drive vehicle. Each wheel position can cause different wear rates and different types of tire wear. It is to your advantage  when  al!  four  tires  wear  together  because as wear reduces tread depth of a tire, it allows tires to respond   to   the   operator's   input   more   quickly, maintains  the  handling,  and  it  helps  increase  the cornering  traction  of  a  tire.  Figure  8-41  shows common tire rotation diagrams. A description of each is as follows. On front-wheel drive vehicles, rotate the tires in a forward cross pattern (A) or the alternative X pattern  (B). On rear-wheel drive vehicles, rotate the tires in a rearward cross pattern (C) or the alternative X pattern  (B). If the vehicle has directional tires, rotate these tires from front to back only and vise versa(D). If the vehicle has nondirectional tires that are a different size from front to rear, rotate these tires from side to side only (E). 8-37