but one is se-riously underinflated; the other tire may be carrying a larger than normal portion of the load. Weâll talk about inflation as a separate subject.3. AIRCRAFt WHEEL ConStRuCtIon.Aircraft wheels are manufactured from either magnesium
aluminum alloy or steel alloy. They operate in a high stress environment and are subject to corrosion and mechanical damage during tire mounting and normal service. Almost all mod-ern wheels are of the split half type wherein the two halves of the wheel are bolted together across the tire beads. Due to manufacturing tolerances
it is essential that the two wheel halves be matched by both manufacturer and part number.The wheels contain the inflation valve for the tire and the fusible plugs de-signed to melt and release tire pressure in a high temperature situation. Some may also contain a pressure relief valve designed to vent excessive inflation pressure.CAutIon. Never attempt to disassemble a wheel without first insuring that the tire is deflated. An inflated aircraft tire is a potentially lethal explo-sive device. At the scene of any aircraft accident
it is standard safety practice to insure that all tires are deflated before the investigation begins.4. AIRCRAFt tIRE ConStRuCtIon.Aircraft tires are designed to withstand very high speeds and very heavy static and dynamic loads â intermittently. By contrast
an automobile tire is designed for much lower speeds and loads; but it is designed to run continuously at a stabilized temperature. An aircraft tire will fail under continuous operation. Exceptionally long taxi distances can fail an aircraft tire.The tread of a tire is rubber followed by one or more layers of tread reinforcing nylon fabric. The strength of the tire is in its plies which are layers of rubber-coated nylon fabric laid diagonally and at 90Â° to each other. Almost all aircraft tires in service today are tubeless.5. tIRE SPECIFICAtIonS.Most tire specification information can be read off the tire sidewall. This includes the manufacturer
speed rating and number of times the carcass has been retreaded if at all. Additional information available from the manufacturerâs data sheets include in-flation pressure
maximum braking load
bottoming load and tire dimension and weight information. Some of these need amplification.A. LoAD RAtInG. This is the maximum load (in pounds) for the ply rating of the tire.B. PLy RAtInG. This is an index of the strength of the tire and is not neces-sarily the number of actual plies in the tire carcass.C. SPEED RAtInG. This is the maximum speed (usually in MPH) to which the tire is qualified.D. mAXImum BRAKInG LoAD. The maximum steady braking load (in pounds) which may be applied to a tire during landing.Figure 16-1. Tire Diameter Mismatch Tolerance.