Which traffic sign refers to the permissible total mass?

Your answer is correct because traffic sign number 2 refers to the permissible total mass of a vehicle. In German traffic rules, this sign shows a restriction for vehicles exceeding the indicated total weight. The main sign with the truck symbol means trucks are prohibited if they exceed the weight shown on the supplementary plate below it (7.5 tons in this case).

Sign number 1 only shows a weight limit but does not specify vehicle type, so it generally restricts all vehicles exceeding the listed total mass from entering. However, in the question, the correct answer specifically refers to permissible total mass for certain vehicles, which is clearly indicated by sign number 2 due to its combination of truck symbol and weight plate.

Understanding these signs helps ensure compliance with weight limits and protects road infrastructure from damage caused by overweight vehicles.