The machine (1) for fitting and removing wheel tyres for vehicles comprises a bearing structure (2), an attachment and rotation arrangement (4) of the rim (C) of a wheel (R) for vehicles, a tool-holder assembly (5) movably associated with the bearing structure (2) and having at least a tool (8, 9, 10) for removing and/or fitting a tyre (P) from/onto the rim (C), an adjustment arrangement (11, 12) able to adjust the relative position between the tool-holder assembly (5) and the rim (C), to place the tool-holder assembly (5) in an optimal operating position wherein the tool (8, 9, 10) is operable to remove and/or fit a tyre (P), and a visual signaling assembly (13, 14) of said optimal position having at least an emitter (13, 14) of a light beam (L1, L2), the optimal operating position being defined when the point of incidence of the light beam (L1, L2) on the wheel (R) coincides with an external point of the edge of the rim (C).