What extinguishing agent must be used in the event of a fire involving wheels/tires? Why?
You can find some discussion in this thread but what you are looking for is
Fire Service manual. Volume 2. Fire Service Operations : aircraft
incidents Home Office - London
HMSO, 12/99. Crown copyright 1999
ISBN 0-11-341192-8; 0113411928
5.4.2 Brake and wheel fires The overheating of brake and wheel assemblies usually follows excessive braking. This can happen on landing when a hydraulic failure reduces the ability of the pilot to utilise control surfaces (flaps) and he feels the aircraft may over run the runway or more often, on an aborted take-off. Quite often tyres will burst or, as the aircraft comes to a standstill, ignite by transference of heat from the brakes. To avoid metal failure, firefighters attending overheated brake and wheel assemblies should usually refrain from applying water and allow natural cooling. If there is fire however, a fine water fog applied from fore and aft of the undercarriage assembly is generally used.