Method of selectively controlling the self-sealing ability of a tyre and self-sealing tyre for vehicle wheels

A self-sealing tyre for vehicle wheels comprising:

• at least one carcass ply, a tread band applied at a radially external position to said carcass ply at a crown region, at least one liner applied at a radially internal position to said carcass ply, a sealing assembly applied at a position radially internal to the liner and axially extending at least over the whole crown region of the tyre,
• wherein said sealing assembly comprises a self-supporting thermoplastic film of a polyamide or polyester material, a layer of sealing material associated with and supported by said self-supporting thermoplastic film,
• wherein the self-supporting thermoplastic film is radially internal to the layer of sealing material and said layer of sealing material is placed directly in contact with the liner,
• wherein said self-supporting thermoplastic film has a thickness ranging from greater than 5 μm to less than 25 μm,
• wherein the self-supporting thermoplastic film has such a stress relaxation relative to time, that in 10 seconds following achievement of an imposed elongation of 110% to 150%, the thermoplastic film shows a reduction of at least 20% of stress necessary for maintaining such an imposed elongation,
• wherein the layer of sealing material consists essentially of a synthetic or natural elastomer material, an optional process oil, an optional tackiness agent, an optional reinforcing filler, and an elastomeric block copolymer, wherein each of said synthetic or natural elastomer material is selected from the group consisting of cis-1,4-polyisoprene, 3,4-polyisoprene, polybutadiene, polybutadiene with a high 1,4-cis content, isoprene/isobutene copolymers, halogenated isoprene/isobutene copolymers, 1,3-butadiene/acrylonitrile copolymers, stirene/1,3-butadiene copolymers, stirene/isoprene/1,3-butadiene copolymers, stirene/1,3-butadiene/acrylonitrile copolymers, and mixtures thereof, and
• wherein said sealing layer has a maximum thickness less than about 6 mm.