Abstract: A tire 1 includes a pair of crown circumferential grooves 30, a pair of shoulder circumferential grooves 31, a crown land portion 40, and a pair of middle land portions 41 and 42, the crown land portion 40 includes a main crown shallow groove 100 and at least two sub-crown shallow grooves 101 and 102 each extending so as to communicate with the crown circumferential groove 30 and the main crown shallow groove 100, the pair of middle land portions 41 and 42 include V-shaped slots 201 and 202, respectively, and the sub-crown shallow grooves 101 and 102 and the slots 201 and 202 are located so as to be substantially point-symmetrical about a midpoint between positions at which the adjacent sub-crown shallow grooves 101 and 102 communicate with the main crown shallow groove 100.

Abstract: A tire comprises a tread portion whose shoulder land part is provided with a narrow circumferential groove having an axially inner wall surface, an axially outer wall surface and a groove bottom including a deepest point. The axially inner wall surface has a radially inner curved portion concaved toward the axially inside, and the axially outer wall surface has a radially inner curved portion concaved toward the axially outside. the radially outer end of the radially inner curved portion of the axially inner wall surface is positioned radially inside the radially outer end of the radially inner curved portion of the axially outer wall surface.

Abstract: A heavy-duty pneumatic tire includes a tread portion including a pair of shoulder land portions. At least one of the pair of shoulder land portions is provided with a narrow groove extending continuously in the tire circumferential direction to divide the shoulder land portion into a main portion and a sacrificial rib located outward in the tire axial direction. The sacrificial rib includes a root portion in a tire radial direction with an axial width Wr, a top surface in the tire radial direction with an axial width Ws, and a ratio Wr/Ws being equal to or more than 1.0. In the shoulder land portion, a shortest distance Lw between the narrow groove and a maximum thickness line that defines a maximum thickness of the shoulder land portion measured in a normal direction to a tire cavity surface is equal to or less than 5.0 mm.

Abstract: A tire 1 includes a pair of crown circumferential grooves 30, a pair of shoulder circumferential grooves 31, a crown land portion 40, and a pair of middle land portions 41 and 42, the crown land portion 40 includes a main crown shallow groove 100 and at least two sub-crown shallow grooves 101 and 102 each extending so as to communicate with the crown circumferential groove 30 and the main crown shallow groove 100, the pair of middle land portions 41 and 42 include V-shaped slots 201 and 202, respectively, and the sub-crown shallow grooves 101 and 102 and the slots 201 and 202 are located so as to be substantially point-symmetrical about a midpoint between positions at which the adjacent sub-crown shallow grooves 101 and 102 communicate with the main crown shallow groove 100.

Abstract: A tire comprises a tread portion whose shoulder land part is provided with a narrow circumferential groove having an axially inner wall surface, an axially outer wall surface and a groove bottom including a deepest point. The axially inner wall surface has a radially inner curved portion concaved toward the axially inside, and the axially outer wall surface has a radially inner curved portion concaved toward the axially outside. the radially outer end of the radially inner curved portion of the axially inner wall surface is positioned radially inside the radially outer end of the radially inner curved portion of the axially outer wall surface.

Abstract: A crankshaft is normally and reversely rotated at a constant speed, during which the singular points of crankshaft driving motor current responding to the drive torque change of the crankshaft are detected. A crankshaft rotational angle reference point is set based on the midpoint between the crankshaft rotational positions obtained when, among these singular points, singular points having the same type appear during the respective normal and reverse rotations. Therefore, the crankshaft rotational angle reference point can be reliably set regardless of the variations and errors.

Abstract: A crankshaft is normally and reversely rotated at a constant speed, during which the singular points of crankshaft driving motor current responding to the drive torque change of the crankshaft are detected. A crankshaft rotational angle reference point is set based on the midpoint between the crankshaft rotational positions obtained when, among these singular points, singular points having the same type appear during the respective normal and reverse rotations. Therefore, the crankshaft rotational angle reference point can be reliably set regardless of the variations and errors.