Pneumatic tire having lug grooves forming a direction tread pattern

A pneumatic tire comprising a tread, the tread having, in a surface thereof:

• lug grooves on one side extending from one axial edge towards an axial center of the tire in such a manner as to intersect with a circumferential direction thereof and lug grooves on the other side extending in a symmetrically opposite direction from the axial center towards the other axial edge of the tire, such that the lug grooves on one side and the lug grooves on the other side form a directional tread pattern;
• and
• three circumferential grooves extending circumferentially around the tire,
• wherein the three circumferential grooves are disposed in a central region, the central region being a region enclosed by two straight parallel lines each passing through a center between contact width center, being defined as a center of a ground contacting area in the axial direction of the tire and a respective contact edge, being defined as an edge of the ground-contacting area in the axial direction of the tire, with shoulder regions being regions outside of the straight lines, and wherein an average contact length (a) of central blocks, which are blocks defined by a central circumferential groove that is a centrally located circumferential groove and intermediate circumferential grooves that are laterally located circumferential grooves of the three circumferential grooves and the lug grooves, and an average contact length (b) of intermediate blocks, which are blocks located in axially outer positions and defined by the laterally located circumferential grooves of the three circumferential grooves and the lug grooves, satisfy a relationship of “0.9·a<b<1.1·a”,
• wherein shoulder grooves are grooves disposed discontinuously in a circumferential direction within a contact patch of the tire, wherein an average groove width of the lug grooves defining shoulder blocks is greater than an average groove width of the lug grooves defining central blocks, wherein a groove width of each of the intermediate circumferential grooves is wider than a groove width of the central circumferential groove, wherein the sum of the cross-sectional areas of the central circumferential groove, the intermediate circumferential grooves, and the shoulder grooves is smaller than the cross-sectional area of the lug grooves, and wherein the groove bottom of each of the lug grooves on the axial center side in the central blocks has a raised groove bottom portion having a cross-sectional area of 10% or more and 90% or less of the cross-sectional area of the respective lug groove,
• a groove depth of the central circumferential groove is deeper than a minimum depth of each of the raised groove bottom portions and less than a maximum depth of each of the lug grooves,
• the central circumferential groove being a circumferential groove located in the axial center of the tire of the circumferential grooves disposed in the central region, the intermediate circumferential grooves being circumferential grooves located in axially outer positions, and the shoulder grooves being circumferential grooves disposed in the shoulder regions, and
• the central blocks being blocks defined by the central circumferential groove, the intermediate circumferential grooves, and the lug grooves, the shoulder blocks being blocks defined by the shoulder grooves and the lug grooves, and the intermediate blocks being blocks defined by the intermediate circumferential grooves, the shoulder grooves, and the lug grooves.