An apparatus for displaying the state of the tire pressure for a vehicle tire of a truck trailer includes a lamp to optically display the tire pressure state. An arm is provided with the lamp arranged thereon. A mount fixes the arm to the truck trailer and the arm is made substantially of an elastomer material so as to cause the arm to be flexibly deformable when colliding with a foreign object. The arm reverts back to its initial configuration after such a collision as a result of its elastic material characteristic.