Which traffic sign refers to the permissible total mass?

Answer 2 is correct because the rectangular supplementary sign with a weight value specifies a permissible mass limit, typically referring to the permissible total mass (zulässige Gesamtmasse) for the vehicles the main sign applies to. “Permissible total mass” means the vehicle’s allowed maximum weight including the vehicle itself, occupants, cargo, and (if applicable) the trailer load, as stated in the registration papers, not the weight you happen to have at that moment.

In contrast, answer 1 (the round sign with “5.5 t”) is a prohibition sign that limits traffic by a weight value in the sign itself, but it’s used as a general restriction sign and not as the “supplementary sign” that explicitly clarifies permissible total mass in combination with a main sign. Rule of thumb: rectangular additional plates with “t” usually clarify which vehicles are affected by the main sign using their permissible total mass.