For a motorcycle to be able to circulate, it is important that it has the appropriate **rear-view mirrors** installed, as these allow the driver to have better visibility and safety while driving.

- **Motorcycles that reach a maximum speed of over 100 km/h** must have **two rear-view mirrors**: one on the left side and one on the right side. This is necessary because at higher speeds, it is crucial to have a clear view of both sides to react quickly to any situation on the road.

- On the other hand, motorcycles that travel at less than 100 km/h are only required to have a rear-view mirror on the left side. This is because at lower speeds, the risk is lower and a single mirror may be sufficient to maintain safety.

Therefore, the correct answer is that the motorcycles that must have at least two rear-view mirrors installed, one on each side, are those that **reach a maximum speed of over 100 km/h**.