Which of the following enhances the stability of a motorcycle?

Proper tire pressure is crucial for enhancing the stability of a motorcycle. When the tires are inflated to the recommended pressure, they maintain optimal contact with the road surface, which improves traction and handling. This ensures that the motorcycle can effectively respond to the rider's inputs, allowing for smoother cornering and better overall control.

In contrast, riding at high speeds does not necessarily enhance stability and can actually increase the risk of losing control, especially if the motorcycle is not designed for such speeds. Loose handlebars can lead to a lack of control, making it difficult for the rider to steer accurately, while an empty fuel tank can cause handling issues as well, as it shifts the weight and balance of the motorcycle. Maintaining proper tire pressure is fundamental to achieving a safe and stable ride.