Process for producing self-sealing tyres, comprising: a) arranging a tyre comprising a crown portion arranged circumferentially around a rotation axis (R) 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 (D) 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 (S), arranged around an axis (A) at a diameter (D1) smaller than the diameter (D) of the annular anchoring portions of the tyre , said support being radially expandable, c) arranging, on the deposition surface (S) of the support, a self-sealing sleeve having cylindrical configuration around said axis (A), said self-sealing sleeve extending along said axis (A) between two circumferential end edges delimiting an axial size (L) 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 (D) 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 (R) 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 (D) 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 (S), arranged around an axis (A) at a diameter (D1) smaller than the diameter (D) of the annular anchoring portions of the tyre , said support being radially expandable, c) arranging, on the deposition surface (S) of the support, a self-sealing sleeve having cylindrical configuration around said axis (A), said self-sealing sleeve extending along said axis (A) between two circumferential end edges delimiting an axial size (L) 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 (D) 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 . <EOS>