Motorcycle

This motor vehicle shown in the photo falls under the category of motor vehicles. Even if the motorcycle is pulling a sidecar or a trailer, it remains a motorcycle.
If a road is closed to motor vehicles with more than two wheels, a motorcycle with a sidecar is not allowed on that road. A motorcycle with a trailer is allowed on that road.
A motorcycle can fall under multiple categories. First and foremost, it is a motor vehicle.
If the motorcycle is carrying a trailer, it falls under the category of motor vehicles with a trailer.

Article 1 of the Road Traffic and Traffic Regulations (RVV).
Motorcycle: a two-wheeled motor vehicle with or without a sidecar or trailer.