A device for assembling and/or disassembling a tyred wheel comprising: - a support component; - an extension or stem component connected to said support component so as to be able to slide with respect to said support component along a sliding direction (A-A), said extension or stem component comprising a first end and a second end and being slidably connected to said support component at said second end or at an intermediate portion extending between said first and said second ends of said extension or stem component; - a working tool articulated to said extension or stem component about at least one articulation axis (y-y, z-z) substantially transverse or orthogonal to said sliding direction (A-A), said working tool being articulated to said extension or stem component so as to be angularly movable with respect to said extension or stem component between a first position or rest position and at least one second position or moving position by means of the reaction force exerted, while the movement of said extension or stem component is driven along said sliding direction (A-A), to a first end or treatment end of said working tool by a rim and/or by a tyre of said tyred wheel, said working tool being articulated to said extension or stem component proximal to said first end of said extension or stem component and distal from said second end of said extension or stem component; - actuation means designed to drive the sliding of said extension or stem component with respect to said support component along said sliding direction (A-A), in that said extension or stem component has a main axis of extension (x-x) substantially aligned with said sliding direction (A-A), in that it comprises a base as well as a column protruding, in use, upwards from said base and supporting said support component, and in that said support component comprises an arm having a longitudinal axis (w-w), whereas said extension or stem component is connected to said arm so that said sliding direction (A-A) of said extension or stem component is substantially transverse or orthogonal to said longitudinal axis (w-w) of said arm. - a support component; - an extension or stem component connected to said support component so as to be able to slide with respect to said support component along a sliding direction (A-A), said extension or stem component comprising a first end and a second end and being slidably connected to said support component at said second end or at an intermediate portion extending between said first and said second ends of said extension or stem component; - a working tool articulated to said extension or stem component about at least one articulation axis (y-y, z-z) substantially transverse or orthogonal to said sliding direction (A-A), said working tool being articulated to said extension or stem component so as to be angularly movable with respect to said extension or stem component between a first position or rest position and at least one second position or moving position by means of the reaction force exerted, while the movement of said extension or stem component is driven along said sliding direction (A-A), to a first end or treatment end of said working tool by a rim and/or by a tyre of said tyred wheel, said working tool being articulated to said extension or stem component proximal to said first end of said extension or stem component and distal from said second end of said extension or stem component; - actuation means designed to drive the sliding of said extension or stem component with respect to said support component along said sliding direction (A-A),