Mexicana and Swissair were tire explosions, not wheelwell fires
Yes, but the tire explosions initiated fires in both cases.
Mexicana: The left main gear brake was overheated during the take-off run. When the aircraft had reached FL310 the heat caused a tyre on the left hand main gear to explode. Fuel and hydraulic lines were ruptured and electrical cables severed resulting in a cabin decompression. An emergency was declared, but spilt fuel ignited and caused a massive fire on board. Control was lost and the aircraft crashed into a mountain.
Swissair: The aircraft's brakes overheated due to the application of full engine power during taxiing. This caused the aluminum wheels to burst, one of them on the runway prior to departure. Upon retraction of the landing gear, the hydraulic lines in the gear bay were damaged. This was caused either by the wheels that had exploded, or the bursting of the other wheel rims during the climb. Subsequently, spilled hydraulic fluid ignited when it came in contact with the overheated landing gear rims. The fire damaged the gear bay, followed by the wing. Finally losing its hydraulic pressure, the aircraft became impossible to control. The cabin and the cockpit were filled with smoke, adding to the predicament of the crew. Control of the aircraft was lost totally, and the ensuing final dive and impact destroyed the aircraft.