Loosening the Tire from the Wheel Rim Cleaning the Wheel Bearings Disassembly of the Wheel Wheel Bearing Inspection Cleaning the Wheel Assembly After inflation and usage, an aircraft tire has a tendency to  adhere to the wheel, and the bead must be broken to remove  the tire. There are mechanical and hydraulic presses designed  for this purpose. In the absence of a device specifically  made for the job, an arbor press can be used with patience  working sequentially around the wheel as close as possible  to the bead.  [Figure 13-63]  As stated above, there should  be no air pressure in the tire while it is being pressed off of  the wheel. Never pry a tire off of the rim with a screwdriver  or other device. The wheels are relatively soft. Any nick or  deformation causes a stress concentration that can easily  lead to wheel failure. Disassembly of the wheel should take place in a clean area on  a flat surface, such as a table. Remove the wheel bearing first  and set aside for cleaning and inspecting. The tie bolts can  then be removed. Do not use an impact tool to disassemble  the tie bolts. Aircraft wheels are made of relatively soft  aluminum and magnesium alloys. They are not designed to  receive the repeated hammering of an impact tool and will  be damaged if used. Clean the wheel halves with the solvent recommended by the  wheel manufacturer. Use of a soft brush helps this process.  Avoid abrasive techniques, materials, and tools, such as  scrapers, capable of removing the finish off of the wheel.  Corrosion can quickly form and weaken the wheel if the  finish is missing in an area. When the wheels are clean, they  can be dried with compressed air.  Common conditions of a bearing that are cause for  rejection are as follows: Once cleaned, the wheel bearing is inspected. There are  many unacceptable conditions of the bearing and bearing  cup, which are grounds for rejection. In fact, nearly any  flaw detected in a bearing assembly is likely to be grounds  for replacement.  The bearings should be removed from the wheel to be  cleaned with the recommended solvent, such as varsol,  naptha, or Stoddard® solvent. Soaking the bearings in  solvent is acceptable to loosen any dried-on grease. Bearings  are brushed clean with a soft bristle brush and dried with  compressed air. Never rotate the bearing while drying with  compressed air. The high-speed metal to metal contact of  the bearing rollers with the race causes heat that damages  the metal surfaces. The bearing parts could also cause  injury should the bearing come apart. Always avoid steam  cleaning of bearings. The surface finish of the metals will  be compromised leading to early failure.  Figure 13-63.  Tire beads must be broken from the wheel to remove the tire. A mechanical removal tool designed for breaking the bead  is shown in (A); a hydraulic press designed with the capacity for large aircraft wheels is shown in (B); and an arbor press is shown in  (C). All are tools available to the technician for this purpose.  13-38 Galling—caused by rubbing of mating surfaces. The metal  gets so hot it welds, and the surface metal is destroyed as the  motion continues and pulls the metal apart in the direction  of motion.  [Figure 13-64] Spalling—a chipped away portion of the hardened surface  of a bearing roller or race.  [Figure 13-65] Overheating—caused by lack of sufficient lubrication results  in a bluish tint to the metal surface. The ends of the rollers 