A method for detecting wheels of a vehicle on a road comprises directing a vehicle classification sensor onto a section of the road and recording a 3D representation of the vehicle, directing a camera onto the section and recording a source 2D image, determining a bounding box circumscribing the 3D representation, a side and four corner points of said bounding box side, identifying corner points in a source 2D image plane, defining four corner points of a rectangle in a destination 2D image plane, calculating a projective transformation between the source corner image points and the destination corner image points, transforming source 2D image pixels to destination 2D image pixels of a first destination 2D image, and detecting the wheels using the destination 2D image.