Method and apparatus for determining the tread depth of a vehicle tire

A method for determining the tread depth of a vehicle tire, with the tire being mounted on a vehicle, comprising the steps wherein

• the tire is rolled over or placed on a measuring station;
• the tread of the tire is optically sensed transversely to the rolling direction of the tire on at least one measuring line, wherein a ray fan extending from a light source being reflected at the tire surface and a signal of the reflected ray fan is recorded by a sensor in a non-orthogonal manner to the tire surface, and wherein measuring is carried out outside a foot print of the tire on the measuring station;
• and
• the signal of the reflected ray fan is evaluated by way of a triangulation method;
• wherein a surface angle of the tire is determined as an angle between a normal to the tire surface and the direction towards the light source or the direction towards the sensor.

An apparatus for determining the tread depth of a vehicle tire, with the tire mounted on a vehicle, comprising

• a measuring station including a light source and a sensor, wherein the light source produces a ray fan extending along at least one measuring line transversely to the rolling direction of the tire and outside a foot print of the tire wherein the sensor records signals of the ray fan reflected from the tire surface in a non-orthogonal manner with respect to the tire surface;
• and
• an evaluation unit for the signals of the ray fan reflected from the tire surface which runs through a triangulation method;
• wherein the measuring station is further configured to determine a surface angle of the tire as an angle between a normal to the tire surface and the direction towards the light source or the direction towards the sensor.