Abstract: A heavy duty pneumatic tire has a belt disposed radially outside a carcass and radially inside a tread portion, the belt having at least one ply of at least one high-elongation steel cord, the high elongation steel cord is formed by twisting at least three waving steel filaments together to form a core and a sheath surrounding the core, the waving filaments change place repeatedly along the longitudinal direction of the cord such that one of the filaments forms the core in a portion, but in a different portion of the cord, the same filament forms part of the sheath, thereby defining a plurality of first parts with the core and a plurality of second parts without the core which are disposed alternately in the longitudinal direction of the cord, and the elongation at break of the high-elongation steel cord is in the range of from 4 to 10%, whereby the resistance to breakage of the steel belt cords is improved and it becomes possible to decrease the belt weight without deteriorating various performances.

Abstract: A heavy duty pneumatic tire comprises a belt disposed radially outside a carcass and radially inside a tread portion, the belt comprising at least one ply of at least one high-elongation steel cord, the high-elongation steel cord being formed by twisting at least three waving steel filaments together to form a core and a sheath surrounding the core. The waving filaments change place repeatedly along the longitudinal direction of the cord such that one of the filaments forms the core in a portion, but in a different portion of the cord, the same filament forms part of the sheath, thereby defining a plurality of first parts with the core and a plurality of second parts without the core which are disposed alternately in the longitudinal direction of the cord. The elongation at break of the high-elongation steel cord is in the range of from 4 to 10%.

Abstract: A radial tire for heavy duty vehicles has a tread surface provided with at least a main groove (4) extending in the tire circumferential direction, a slot (9) with a slot width (HS) of 3 to 6 mm, and siping (11). A groove bottom (3) of the main groove (4) is in a zigzag form, and a groove upper edge line (8) of the main groove (4) on the tread surface has outer and inner groove upper edge line (M1, V1) repeated alternately and each extending in the tire circumferential direction. The distance (hu) in the tire axial direction between the outer and inner groove upper edge lines (M1, V1) is smaller than the deflection width (hl) of the zigzag groove bottom. The groove wall of the main groove (4) has hill protrusions (6) each having an inclined groove wall part (5) extending from the external angle portion (M) of the zigzag groove bottom to the outer groove upper edge line (M1).