What is the maximum permissible width of this truck tractor with mounted implement?

You answered correctly. For a truck tractor with a mounted implement (like agricultural machinery), the maximum legal width allowed in Germany is 3.0 meters. This rule exists to ensure that large agricultural vehicles can safely use public roads without creating excessive hazards for other road users. If the width exceeds 3.0 meters, special permits and precautions are required. Always remember this rule when operating or encountering wide agricultural vehicles on the road.