Which of the following is an indication of hot brakes?

Extreme heat is a primary indication of hot brakes, as it occurs when the braking system has generated excessive heat due to prolonged or intense braking. In aircraft operations, particularly during landing or taxiing, the brakes can become very hot due to the friction generated. This is often evident when the brake components reach temperatures that can lead to potential failure or performance issues, making it essential for crew members to monitor brake temperatures closely.

Low tire pressure and inflated tires do not directly indicate hot brakes; rather, they are more related to the tire condition and can have different implications for aircraft safety and performance. Additionally, the presence of smoke, often associated with overheating components, is a key warning sign, and thus no visible smoke does not indicate hot brakes. Therefore, extreme heat serves as the clear indicator in this scenario.