Car tyre having a tread comprising a central portion located across an equatorial plane (X-X), a first shoulder portion located towards an outer side of the tyre and a second shoulder portion located towards an inner side of the tyre; first circumferential grooves (3, 6) axially delimiting the first shoulder portion and the second shoulder portion with respect to the central portion of the tread; wherein: - said first shoulder portion and said second shoulder portion comprise a plurality of first transverse grooves (56, 66) having a first end located substantially at the respective edge of the tread, having a width greater than or equal to about 4 mm and an axial extension equal to at least 50% of the width of the shoulder portion in which they are located; - the number of said first transverse grooves (56, 66) of the first shoulder portion is lower than the number of said first transverse grooves of the second shoulder portion; - said central portion comprises at least one circumferential rib (9, 10, 11), comprising a plurality of second transverse grooves (16, 17, 18); - said central portion comprises a second circumferential groove and two circumferential ribs (10, 11); - each circumferential rib (9, 10, 11) of the central portion has a predetermined void-to-rubber ratio, said void-to-rubber ratio being greater in the rib which is closest to the inner side of the tyre than the other ribs; characterized in that: - said second transverse grooves (16, 17, 18) have a maximum width smaller than or equal to about 3 mm and define in said at least one circumferential rib (9, 10, 11) a void-to-rubber ratio smaller than 0.06; - said second transverse grooves (16, 17, 18) comprise a first substantially straight segment extending over at least 50% of the total extension of the second transverse grooves (16, 17, 18); said first substantially straight segment has an extension smaller than 95% of the total extension of the second transverse grooves (16, 17, 18). - said first shoulder portion and said second shoulder portion comprise a plurality of first transverse grooves (56, 66) having a first end located substantially at the respective edge of the tread, having a width greater than or equal to about 4 mm and an axial extension equal to at least 50% of the width of the shoulder portion in which they are located; - the number of said first transverse grooves (56, 66) of the first shoulder portion is lower than the number of said first transverse grooves of the second shoulder portion; - said central portion comprises at least one circumferential rib (9, 10, 11), comprising a plurality of second transverse grooves (16, 17, 18); - said central portion comprises a second circumferential groove and two circumferential ribs (10, 11); - each circumferential rib (9, 10, 11) of the central portion has a predetermined void-to-rubber ratio, said void-to-rubber ratio being greater in the rib which is closest to the inner side of the tyre than the other ribs; characterized in that: - said second transverse grooves (16, 17, 18) have a maximum width smaller than or equal to about 3 mm and define in said at least one circumferential rib (9, 10, 11) a void-to-rubber ratio smaller than 0.06; - said second transverse grooves (16, 17, 18) comprise a first substantially straight segment extending over at least 50% of the total extension of the second transverse grooves (16, 17, 18); said first substantially straight segment has an extension smaller than 95% of the total extension of the second transverse grooves (16, 17, 18). - said second transverse grooves (16, 17, 18) have a maximum width smaller than or equal to about 3 mm and define in said at least one circumferential rib (9, 10, 11) a void-to-rubber ratio smaller than 0.06; - said second transverse grooves (16, 17, 18) comprise a first substantially straight segment extending over at least 50% of the total extension of the second transverse grooves (16, 17, 18); said first substantially straight segment has an extension smaller than 95% of the total extension of the second transverse grooves (16, 17, 18).