In case of hot brakes without fire, the best option is natural cooling, possibly assisted by a fan.
Here are some reference documents about the use of water mist when a wheel assembly fire develops as a consequence of hot brakes.
ICAO DOC 9137-AN/898
Airport Services Manual
Part 1 - Rescue and Fire Fighting
3rd Edition - 1990
12.2.3 Hot brakes and wheel fires.
The heating of aircraft wheels and tires presents a potential explosion hazard, greatly increased when fire is present. In order not to endanger the members of the airport rescue and fire fighting service needlessly, it is important to distinguish between hot brakes and brake fires. Hot brakes will normally cool by themselves without the use of an extinguishing agent. Most aircraft operating manuals for propeller driven aircraft recommend that flight crew members keep the propeller forward of the fire turning fast enough to provide an ample cooling airflow. Most wheels of jet aircraft have fusible plugs which will melt at about 177°C and deflate the tire before dangerous pressures are reached. When responding to a wheel fire, airport rescue and fire fighting members should approach the wheels with extreme caution in a fore or aft direction, never from the side in line with the axle. Since the heat is transferred to the wheel from the brake it is essential that the extinguishing agent be applied to this area. If further cooling is desired after extinguishment of the fire, the agent should be
directed at the brake area only.
12.2.4 Too rapid cooling of a hot wheel, especially if localized, may cause explosive failure of the wheel. Solid streams of water should not be used except as a last resort. Water fog can be used but intermittent application of short bursts of 5 to 10 seconds every 30 seconds is recommended. Dry chemical has limited cooling capacity but is an effective extinguishing agent. Once the tires are deflated, any extinguishing agent may be safely used as there is no further danger of explosion.
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.
NAVAIR 00-80R-14
NATOPS U.S. NAVY AIRCRAFT FIREFIGHTING AND RESCUE MANUAL
15 OCTOBER 2003
6.6.1 Wheel Assembly Fires.
3. The following warnings, caution, and note pertain
to all aspects of wheel assembly firefighting
operations:
- Rapid cooling may cause an explosive failure of a wheel assembly.
- When water fog is used on a wheel assembly fire, an intermittent application of short bursts (5 to 10 seconds) every 30 seconds should be used.
The IFSTA Aircraft Rescue and Fire Fighting manual has similar information.
The FAA Aircraft Rescue and Firefighter Training CBT states that "Hot brakes should be allowed to cool naturally. If wheel grease or tires start to catch fire, use water to cool and extinguish the fire".
Boeing even suggests using water mist also to cool hot brakes and plenty of water in case of a wheel assembly fire. See the note on the bottom-right corner of page 1 in each of the crash charts available here:
site:www.boeing.com arff "water mist" - Google Search