Abstract: A pneumatic tire has a tread having adjacent rib-shaped land portions (4) with circumferential grooves (3) therebetween. Annular elongate projection portions (5, 5) project toward each other from adjacent rib-shaped land portions (4). The elongate projection portions (5, 5) confronting each other are disposed with a spacing therebetween such that their mutually confronting tip surfaces (5s, 5s) make contact with each other due to elastic deformation of the rib-shaped land portions (4, 4) at the time of grounding of the tire. An inside groove space (6) is formed on a radially inner side of the confronting elongate projection portions (5, 5) and an outside groove space (7) is formed on a radially outer side of the elongate projection portions (5, 5). The tip surfaces (5s) of the elongate projection portions (5) are formed with a plurality of communication recesses (9) providing communication between the inside and outside groove spaces (6, 7).

Abstract: The present invention provides a steel wire rod with stable workability. The steel wire rod has steel components containing, by mass %, C: 0.20 to 0.60%, Si: 0.15 to 0.30%, Mn: 0.25 to 0.60%, P: ?0.020%, S: ?0.010%, and a balance of Fe and unavoidable impurities, and an internal microstructure including cementite, in which by number ratio, 80% or more of the cementite in a cross-section vertical to a longitudinal direction of the wire rod has a short axis of 0.1 ?m or less and a ratio of a long axis to the short axis, defined as an aspect ratio, of 2.0 or less.

Abstract: A high-strength flat steel wire contains, by mass %: C: 0.25 to 0.60%; Si: greater than 0.50% and less than 2.0%; Mn: 0.20 to 1.50%; S: 0.015% or less; P: 0.015% or less; Cr: 0.005 to 1.50%; Al: 0.005 to 0.080%; N: 0.0020 to 0.0080%; and one or two of Ca: 0 to 0.0050% and Mg: 0 to 0.0050% to satisfy [Ca]+[Mg]>0.20×[S], with the balance composed of Fe and impurities, the high-strength flat steel wire has tensile strength of 1000 MPa or more, an average value of Hv hardness measured in a cross section perpendicular to a longitudinal direction of 320 or more and less than 450, a standard deviation ?Hv of the measured value of 15 or less, and a width/thickness ratio of not less than 1.5 nor more than 10. [Ca], [Mg], and [S] represent contents of respective elements by mass %.

Abstract: A pneumatic tire has a tread having adjacent rib-shaped land portions (4) with circumferential grooves (3) therebetween. Annular elongate projection portions (5, 5) project toward each other from adjacent rib-shaped land portions (4). The elongate projection portions (5, 5) confronting each other are disposed with a spacing therebetween such that their mutually confronting tip surfaces (5s, 5s) make contact with each other due to elastic deformation of the rib-shaped land portions (4, 4) at the time of grounding of the tire. An inside groove space (6) is formed on a radially inner side of the confronting elongate projection portions (5, 5) and an outside groove space (7) is formed on a radially outer side of the elongate projection portions (5, 5). The tip surfaces (5s) of the elongate projection portions (5) are formed with a plurality of communication recesses (9) providing communication between the inside and outside groove spaces (6, 7).

Abstract: The present invention provides a steel wire rod with stable workability. The steel wire rod has steel components containing, by mass %, C: 0.20 to 0.60%, Si: 0.15 to 0.30%, Mn: 0.25 to 0.60%, P: 0.020%, S: 0.010%, and a balance of Fe and unavoidable impurities, and an internal microstructure including cementite, in which by number ratio, 80% or more of the cementite in a cross-section vertical to a longitudinal direction of the wire rod has a short axis of 0.1 ?m or less and a ratio of a long axis to the short axis, defined as an aspect ratio, of 2.0 or less.