Pneumatic tire having ground contacting area

A pneumatic tire comprising a tread part having two circumferential grooves continuously extending in the circumferential direction, one of said circumferential grooves being disposed on one side of the tire's equator and the other of the circumferential grooves being disposed on the other side of the tire's equator so as to divide the tread part into a pair of shoulder parts, which are located outside outer bottom edges of the circumferential grooves in the axial direction of tire, and a central part, the central part being located between inner bottom edges of the circumferential grooves in the axial direction of the tire;

• wherein
• the central part has a surface configured by an arc of a single radius of curvature R1 composed of
• a pair of inner groove walls, each of the inner groove walls extending inward in the tire's axial direction from the inner bottom edges, and
• a central ground-contacting surface smoothly connected between the pair of the inner groove walls,
• the radius of curvature R1 is in a range of 0.45 to 0.55 times a ground-contact tread width TW,
• the central ground-contacting surface is substantially in contact with a virtual tread line between outer surfaces of the shoulder parts, and
• when the tire is mounted on a regular rim, inflated with regular internal pressure and applied with normal load,
• a ground-contacting area Fc where the central part contacts with the ground has a length Lc in the tire's circumferential direction which is 0.94 to 0.96 times a length Ls in the tire's circumferential direction of a ground-contacting area FS where the shoulder part contacts with the ground.