A tread for a heavy truck tire, comprising: an upper surface that is configured for engaging ground, wherein the tread has a radial direction, an axial direction, and a circumferential direction, wherein the tread is directional such that the tread is configured for having a rolling direction that extends in the circumferential direction; a J shaped sipe, comprising: a trailing edge, a leading edge, wherein the trailing edge is forward of the leading edge in the rolling direction; a main portion that extends from the upper surface, wherein the main portion has an opening at the upper surface and a bottom end opposite the opening in the radial direction; and a curved portion that extends from the bottom end of the main portion wherein the curved portion has a bottom curved wall that has a radius r 1, wherein the curved portion extends from the bottom end of the main portion forward in the rolling direction, wherein the curved portion has a curved portion end, wherein the curved portion has a top curved wall that faces the bottom curved wall wherein the curved portion has a curved portion thickness t2 that is a distance from the top curved wall to the bottom curved wall and is less than or equal to 1 millimeter, characterized in that the curved portion has different cross-sectional sizes at different points along an axial width of the J shaped sipe such that the curved portion has at least one curved thicker gapped zone and at least one curved thinner gapped zone. an upper surface that is configured for engaging ground, wherein the tread has a radial direction, an axial direction, and a circumferential direction, wherein the tread is directional such that the tread is configured for having a rolling direction that extends in the circumferential direction; a J shaped sipe, comprising: a trailing edge, a leading edge, wherein the trailing edge is forward of the leading edge in the rolling direction; a main portion that extends from the upper surface, wherein the main portion has an opening at the upper surface and a bottom end opposite the opening in the radial direction; and a curved portion that extends from the bottom end of the main portion a trailing edge, a leading edge, wherein the trailing edge is forward of the leading edge in the rolling direction; a main portion that extends from the upper surface, wherein the main portion has an opening at the upper surface and a bottom end opposite the opening in the radial direction; and a curved portion that extends from the bottom end of the main portion wherein the curved portion has a bottom curved wall that has a radius r 1, wherein the curved portion extends from the bottom end of the main portion forward in the rolling direction, wherein the curved portion has a curved portion end, wherein the curved portion has a top curved wall that faces the bottom curved wall wherein the curved portion has a curved portion thickness t2 that is a distance from the top curved wall to the bottom curved wall and is less than or equal to 1 millimeter, characterized in that the curved portion has different cross-sectional sizes at different points along an axial width of the J shaped sipe such that the curved portion has at least one curved thicker gapped zone and at least one curved thinner gapped zone.