A method for the optical determination of correction planes in a rotating element in the form of a rim of different sizes of a vehicle wheel used in the process of balancing in diagnostic devices equipped with a system that has at least one video camera, at least one line projector, a monitor screen and a computer by means of which these component elements of the system are controlled, the method consisting in that the rotating element in the form of a rim of different sizes of a vehicle wheel is placed on the shaft of a diagnostic device in such a manner that the rotating element in the form of a rim of different sizes of a vehicle wheel is perpendicular to the axis of the shaft of a diagnostic device, characterized in that, prior to placing the rotating element in the form of a rim of different sizes of a vehicle wheel on the shaft of the diagnostic device, an area of measurement space is determined in such a manner that a virtual rotating element (EW') in the form of a plane is imposed on the shaft of a diagnostic device wherein the said virtual rotating element (EW') in the form of a plane is placed perpendicularly to the axis of the shaft of the diagnostic device and is located at a minimum distance D 1 from the diagnostic device and on such a situated virtual rotating element (EW') in the form of a plane there is marked a minimum value of radius r 1 relative to the axis of the shaft of a diagnostic device, and subsequently the assigned pixel value P 1 (x 1, y 1) for that radius r 1 is read on the monitor screen, this operation is repeated for subsequent radiuses r n, and finally for the maximum radius value r m and then is performed each time for subsequent distance D n in relation to distance D 1 wherein this operation involves displacing the above-mentioned virtual rotating element (EW') in the form of a plane along the axis of the shaft of the diagnostic device up to maximum distance D m from the diagnostic device obtaining in such a way a determined area of measurement space in form pre-determined pixels P n of the monitor screen having coordinates x n and y n are assigned to a set of points in the area of measurement space, which pixels are then assigned pre-determined values of radiuses r n from the axis of the shaft of the diagnostic device and values of the distance D n of line projected each time by the line projector on the said virtual rotating element (EW') in the form of a plane from the diagnostic device, and in such determined area of measurement space the rotating element in the form of a rim of different sizes of a vehicle wheel is placed on the shaft of the diagnostic device onto which a line is projected by the line projector, and subsequently the view of the rotating element in the form of a rim of different sizes of a vehicle wheel is transmitted by means of the video camera to the monitor screen together with the image of the projected line, and thus the run of the line is obtained which maps a change in the value of radius r n from the axis of the shaft of the diagnostic device and the value of distance D n of the rotating element in the form of a rim of different sizes of a vehicle wheel from the diagnostic device in the defined area of measurement space, and subsequently a specific pixel P n which is a pixel number on the matrix of the monitor screen having coordinates x n and y n is indicated on the monitor screen, which corresponds to the value of radius r n from the axis of the shaft of the diagnostic device and the value of distance D n of the rotating element in the form of a rim of different sizes of a vehicle wheel from the diagnostic device, which values are used to determine correction planes of the rotating element in the form of a rim of different sizes of a vehicle wheel.