Taking a groove side-wall to a position at a groove depth from a tread face of lug groove as a tread-in side first inclined portion, and taking a groove side-wall from the position at groove depth to a groove bottom as a tread-in side second inclined portion, then the following A1 is set less than the following B1. When viewed in cross-section orthogonal to a length direction of the lug groove: A1 is an area of a region enclosed by an imaginary line passing through an end portion on a tread face side of the tread-in side first inclined portion and perpendicular to the tread face, by an imaginary line passing through an end portion on a groove bottom side of the tread-in side first inclined portion and orthogonal to the imaginary line, and by the tread-in side first inclined portion; and B1 is an area of a region enclosed by an imaginary line passing through an end portion on a tread face side of the tread-in side second inclined portion and perpendicular to the tread face, by an imaginary line passing through the deepest portion of the lug groove and parallel to the tread face, and by the tread-in side second inclined portion.

Tread (10) for agricultural tire (1) comprising a plurality of lugs protruding from the ground of the tread (11) in radially outer direction extending at a given inclination angle from a central portion of the tread toward both axial ends of the tread and alternately arranged at given intervals in the circumferential direction on one side and on the other with respect to the equatorial plane of the tire. The lugs (2) comprising a stepping-in surface (21) wherein the stepping-in surface (21) of at least one lug (2) comprises on its sidewall a first radially outer, concave surface (211) and a second, radially inner, concave surface (212) intersecting each other in a transition point (D) when viewed in a circumferential section.

A pneumatic tire has a tread face, a plurality of main grooves extending in a tire circumferential direction in the tread face, and a plurality of land lines defined by the plurality of main grooves on the tread face. At least one of the plurality of land lines protrudes outward in a tire diametrical direction from a profile line. A top face of a central portion of the land line in a width direction is formed in an arc shape protruding outward in the tire diametrical direction in a section along a tire meridian. Top faces of opposite end portions of the land line in the width direction are formed in arc shapes protruding inward in the tire diametrical direction in the section along the tire meridian.

In a pneumatic tire, a groove depth H1 of each of first and second inclined lug grooves over an entire region from an opening portion to a corresponding one of first or second circumferential main grooves to a terminating end portion within a center land portion has a relationship with a maximum groove depth Hg of the corresponding one of the first or second circumferential main grooves represented by 0.80H1/Hg1.00. Additionally, a maximum groove depth H2 of each of first and second lateral grooves has a relationship with a groove depth H1e at a terminating end portion of the corresponding one of the first and second inclined lug grooves represented by 0.70H2/H1e0.90.

A heavy-duty tire includes a tread part formed such that the tread part includes a crown profile including tire equator, and a pair of shoulder profiles extending from outer sides of the crown profile to tread edges. In a tire cross section including tire rotation axis in 5% internal pressure state in which the tire is mounted to a normal rim, filled with air at internal pressure of 5% of normal internal pressure and loaded with no load, each of the crown and shoulder profiles has an arc shape convex toward tire radial direction outer side such that ratio Rc/Rs of curvature radius Re of the crown profile to curvature radius Rs of each shoulder profile is 7.0 or more, and a tire axial direction distance from the equator to a connecting point between the crown profile and each shoulder profile is 0.70 or more times a tread half width.

A tire comprises a tread portion 2 provided with a first main groove 3 and a second main groove 4 each extending in a zigzag manner and a land region 10 defined between them. The land region 10 is provided with a longitudinal sipe 15 extending in a zigzag manner in the tire circumferential direction, first lug grooves 16, and second lug grooves 17. The land region 10 comprises first blocks 21 divided by the longitudinal sipe 15 and the first lug grooves 16, and second blocks 22 divided by the longitudinal sipe 15 and the second lug grooves 17. Each of the first blocks 21 and the second blocks 22 is provided with not less than three transverse sipes 25 extending across the entire width of the each of the first blocks 21 and the second blocks 22.

Tire (1) for an agricultural vehicle, and more particularly the tread (2) thereof, has improved traction in the field, while reducing the sensitivity of the lugs (3) to attack by stubble. Each lug (3) comprises first lug portion (31), having height H1, and second lug portion (32), having height H2 and having a mean angle of inclination A2 with respect to circumferential direction (XX) of the tire. The first lug portion (31) is comprised of a radial superposition of N layers C1.sub.i (33), where i varies from 1 to N, each having a height H1.sub.i, each layer C1.sub.i having a mean angle of inclination A1.sub.i strictly less than the mean angle of inclination A2, and, when N is strictly greater than 1, the angle A1.sub.j relative to a layer C1.sub.j, where j varies from 1 to N1, is strictly less than the angle A1.sub.j+1 relative to the layer C1.sub.j+1.

A pneumatic tire includes a tread; sidewalls; and beads. Lug grooves are formed in the tread inclining symmetrically about an equator, an inclination angle of the lug grooves relative to the lateral direction being 1545. A width W1 of the lug grooves at the tread edge and an interval W2 between the lug grooves at the tread edge satisfying 0.7W1/W21.5. Shoulder grooves connecting lug grooves are inclined in an opposite direction to the lug grooves have an inclination angle relative to the lug grooves being 80100, a center position of the shoulder grooves being 15% to 35% of tread width TW from the equator. An area A1 of the shoulder grooves and an area A2 of shoulder blocks satisfy 0.2A1/A20.6. A groove area ratio of the tread is 0.4 to 0.7.

A pneumatic tire includes a tread; sidewalls; beads inward of the sidewalls; lug grooves formed in the tread and inclined symmetrically about the equator, an inclination angle of the lug grooves with respect to the lateral direction being 1545; and shoulder grooves connecting the lug grooves and inclined in an opposite direction to the lug grooves, a center line of the shoulder grooves at both sides meeting with two of the lug grooves at intersection points. A difference between distances L1, L2 from the equator to the intersection points and a tread width TW satisfy TW0.03|L1L2|TW0.2. An average value of the distances and the tread width TW satisfy TW0.15(L1+L2)/2TW0.35. A groove area ratio of the tread is from 0.4 to 0.7.

A pneumatic tire includes a narrow groove on a tread surface, inclined from the tire circumferential direction, groove width being smaller than groove depth, and an air inflow part opening to the tread surface and formed on one of the opposing groove walls. At least one end of the narrow groove is a terminal end. The air inflow part is disposed at the terminal end of the narrow groove, and in a development plan view of the tread surface, XOY is an acute angle, where O is an intersection between a widthwise center line of the air inflow part and a groove widthwise center line of the narrow groove, X is a terminal endpoint of the air inflow part along the widthwise center line of the air inflow part, and Y is a lengthwise center point of the narrow groove along the groove widthwise center line.