1. A device for measuring characteristic angles and dimensions of wheels, steering system and chassis of vehicles in general, comprising a pair of three-dimensional optical readers for each axle of the vehicle, the three-dimensional optional readers being functionally connected to a computer and arranged peripherally to a vehicle mutually opposite with respect to each axle of the vehicle whose dimensions and characteristic angles of wheels, steering system and chassis are to be measured, each optical reader comprising at least one camera, such that each camera is in each optical reader framing at least one wheel of said vehicle for the three-dimensional acquisition of an image of said at least one wheel, each one of said three-dimensional optical readers being further provided with at least one fixed target for the setting and calibration of said measurement device, wherein at least one camera of each one of said three-dimensional optical readers is arranged in such a manner as to frame directly at least one fixed target of another one of said three-dimensional optical readers, and wherein there is one camera of at least one of said three-dimensional optical readers arranged in such a manner as to frame directly at least two fixed targets of another two of said three-dimensional optical readers arranged on the opposite side of the vehicle, one along the same axle of the vehicle and the other along a different axle of the vehicle, with respect to the three-dimensional optical reader being considered, for the setting and calibration of said measurement device by three-dimensional acquisitions of said fixed targets performed by said at least one camera.