Process for producing self-sealing tyres, comprising: a) arranging a tyre comprising a crown portion arranged circumferentially around a rotation axis of the tyre and two lateral portions which respectively extend on axially opposite sides of the crown portion, wherein each lateral portion terminates in an annular anchoring portion having a diameter and wherein the crown portion has a radially inner crown surface, b) arranging a support having cylindrical configuration and exhibiting a radially outer deposition surface, arranged around an axis at a diameter smaller than the diameter of the annular anchoring portions of the tyre, said support being radially expandable, c) arranging, on the deposition surface of the support, a self-sealing sleeve having cylindrical configuration around said axis, said self-sealing sleeve extending along said axis between two circumferential end edges (20a, 20b) delimiting an axial size of said self-sealing sleeve, d) introducing the support carrying the self-sealing sleeve within the tyre until it is arranged in a position coaxial with the crown portion and radially internal with respect thereto, e) radially expanding said support within the tyre up to reaching an intermediate configuration of the self-sealing sleeve in which the self-sealing sleeve partially adheres to the radially inner crown surface, f) radially contracting said support to a diameter smaller than the diameter of the annular anchoring portions of the tyre and extracting said support from the tyre, releasing the self-sealing sleeve partially adhering to the radially inner crown surface, g) introducing a rolling device within the tyre, h) executing a rolling action on the self-sealing sleeve up to reaching a final configuration of the self-sealing sleeve in which it completely adheres to the radially inner crown surface. a) arranging a tyre comprising a crown portion arranged circumferentially around a rotation axis of the tyre and two lateral portions which respectively extend on axially opposite sides of the crown portion, wherein each lateral portion terminates in an annular anchoring portion having a diameter and wherein the crown portion has a radially inner crown surface, b) arranging a support having cylindrical configuration and exhibiting a radially outer deposition surface, arranged around an axis at a diameter smaller than the diameter of the annular anchoring portions of the tyre, said support being radially expandable, c) arranging, on the deposition surface of the support, a self-sealing sleeve having cylindrical configuration around said axis, said self-sealing sleeve extending along said axis between two circumferential end edges (20a, 20b) delimiting an axial size of said self-sealing sleeve, d) introducing the support carrying the self-sealing sleeve within the tyre until it is arranged in a position coaxial with the crown portion and radially internal with respect thereto, e) radially expanding said support within the tyre up to reaching an intermediate configuration of the self-sealing sleeve in which the self-sealing sleeve partially adheres to the radially inner crown surface, f) radially contracting said support to a diameter smaller than the diameter of the annular anchoring portions of the tyre and extracting said support from the tyre, releasing the self-sealing sleeve partially adhering to the radially inner crown surface, g) introducing a rolling device within the tyre, h) executing a rolling action on the self-sealing sleeve up to reaching a final configuration of the self-sealing sleeve in which it completely adheres to the radially inner crown surface.