NOTE: You should ensure bearings are completely dry before packing (them with lubricant. You should also spread a thin layer of grease on the bearing cups. Inspect the grease retainers for evidence of deterioration, contamination, or water saturation. You should replace them if necessary. Presoak the retainers with VV-L-800 oil prior to installing them. Refer to the NA 01-1A-503 manual for more detailed information on wheel bearing maintenance. Corrosion and Physical Damage Blendout Limited and isolated corrosion and physical damage should be blended. Wheel rims, outside ends of bearing hubs, nicks, gouges, and pock marks are not considered significant unless the defect is deeper than 0.020 of an inch. The defect should not be blended out unless there is active corrosion in the defect. However, all burrs must be removed. Corrosion or other defects should be blended out not to exceed a maximum of one-sixteenth of an inch. All damage must be removed within this allowance. The maximum depth of blendout for all other wheel areas is 0.010 of an inch. The rims, bearing hub ends, and tire bead area can be blended out with a medium or fine cut, half-round or round tile. You should lightly file the damaged area to remove the defects. After the defects have been removed, you should hand polish the areas with 320 or finer grit aluminum oxide (P-C-451). All file marks should be removed. The areas should be painted according to NAVAIR 04-10-1 and NAVAIR 01-1A-509. Matching Wheel Halves Split rim wheels are manufactured and assembled as a matched assembly. Each half will have the same serial number. If a wheel half is rejected at the IMA, the remaining half may be matched to a serviceable replacement to make a complete assembly. When you combine unmatched wheel halves, each half must have the same part number. Every effort should be made to keep the manufacture dates of each half as close as possible. Each half of this wheel assembly will now have different serial numbers, which is acceptable. AIRCRAFT TIRES Learning Objective: Recognize the proce- dures for dismounting, mounting, and inflating aircraft tires. You should be able to identify various tire markings and determine preventive maintenance requirements indicated by tire tread wear. Proper care and maintenance of tires have always been important items in aircraft maintenance. Because of the modern fast-landing aircraft, careful tire maintenance has become increasingly important. Aircraft tires are built to withstand a great deal of punishment, but only by proper care and maintenance can they give safe and dependable service. These designations refer to construction features and the types of tire casings with which they are used. The dimensions used to identify wheels are not necessarily the dimensions of the wheels themselves. Instead, they refer to dimensions of the tire. Tire size designations are discussed later. TIRE CONSTRUCTION Figure 11-10 shows the construction details of a tube-type aircraft tire.    Tubeless tires are similar to tube tires except they have a rubber inner liner that is mated to the inside surface of the tire. The rubber liner helps retain air in the tire. The beaded area of a tubeless tire is designed to form a seal with the wheel flange. Wear indicators have been built into some tires as an aid in measuring tread wear. These indicators are holes in the tread area or lands in the bottom of the tread grooves. The cord body consists of multiple layers of nylon with individual cords arranged parallel to each other and completely encased in rubber. The cord fabric has its strength in only one direction. Each layer of coated fabric constitutes one ply of the cord body. Adjacent cord plies in the body are assembled with the cords crossing at nearly right angles to each other. This arrangement provides a strong and flexible tire that distributes impact shocks over a wide area. The functions of the cord body are to give the tire tensile strength, to resist internal pressures, and to maintain tire shape. The tread is a layer of rubber on the outer surface of the tire. It protects the cord body from abrasion, cuts, bruises, and moisture. It is the surface that contacts the ground. 11-10