Taking a groove side-wall to a position at 1/2 a groove depth from a tread face (12A) of lug groove (16) as a tread-in side first inclined portion (16Fa), and taking a groove side-wall from the position at 1/2 groove depth to a groove bottom as a tread-in side second inclined portion (16Fb), 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 (16): A1 is an area of a region enclosed by an imaginary line (FL3) passing through an end portion on a tread face side of the tread-in side first inclined portion (16Fa) and perpendicular to the tread face (12A), by an imaginary line (FL5) passing through an end portion on a groove bottom side of the tread-in side first inclined portion (16Fa) and orthogonal to the imaginary line (FL3), and by the tread-in side first inclined portion (16Fa); and B1 is an area of a region enclosed by an imaginary line (FL4) passing through an end portion on a tread face (12A) side of the tread-in side second inclined portion (16Fb) and perpendicular to the tread face (12A), by an imaginary line (FL6) passing through the deepest portion of the lug groove (16) and parallel to the tread face (12A), and by the tread-in side second inclined portion (16Fb).