Patent ID: 8261791

Claim:
A pneumatic tire with a nominal width of not less than 255 mm, an outside diameter of not less than 720 mm, and an aspect ratio of not more than 55%, and having a designated direction of sides thereof for mounting the tire on a vehicle, in its tread section, the pneumatic tire comprising: five main grooves each extending in the tire's circumferential direction; six land portions defined by the five main grooves, wherein each of shoulder land portions located at opposite outermost sides in the tire's width direction is divided into a narrow rib portion with a width of not less than 10 mm but not more than 15 mm on a side closer to its neighboring main groove and a block portion on a side closer to a corresponding outer edge of the tread section, by a narrow groove which extends in the tire's circumferential direction, and which has a depth of less than 50% of that of its neighboring main groove, wherein the remaining four land portions interposed between the shoulder land portions each have a width of not less than 20 mm but not more than 26 mm, wherein, out of the remaining four land portions, a land portion located closest to an outside of the vehicle includes a plurality of lateral grooves, at least one of said lateral grooves being open to any one of its two neighboring main grooves and at least another one of the lateral grooves being open to the other of the two neighboring main grooves, but not entirely crossing the land portion located closest to the outside of the vehicle, wherein some lateral grooves open to one of the two neighboring main grooves which is closer to a center of the vehicle has a depth of 60% to 90% of that of the main groove closer to the center of the vehicle, and wherein the other lateral grooves open to the other of the two neighboring main grooves which is closer to the outside of the vehicle has a depth of 10% to 30% of that of the main groove closer to the outside of the vehicle.