What is the primary function of fusible plugs in aircraft wheels?

The primary function of fusible plugs in aircraft wheels is to reduce air pressure to prevent blowouts. These plugs are designed to melt at a specific temperature, allowing the air inside the tire to escape if it becomes too hot. This is crucial because excess heat can build up in the wheel assembly due to braking or other factors, potentially leading to tire blowouts which can be dangerous during takeoff, landing, or taxiing. By relieving the pressure in this way, fusible plugs help to avoid catastrophic failures, thereby enhancing safety.

The other options do not align with the specific role of fusible plugs, as they do not contribute to increasing tire pressure, enhancing braking performance, or directly indicating tire temperature. Their primary purpose is indeed to act as a safety measure against overheating and consequent blowouts.