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A pneumatic tire is cured and molded by a sectional type tire mold including an annular side mold section having a tread forming surface for forming a tread surface, the side mold section comprising a plurality of sectors into which the side mold section is divided along a circumferential direction

A pneumatic tire is cured and molded by a sectional type tire mold including an annular side mold section having a tread forming surface for forming a tread surface, the side mold section comprising a plurality of sectors into which the side mold section is divided along a circumferential direction of the side mold section. A tread surface, which has first regions formed by sector divisional position vicinity regions of the side mold section and second regions formed by sector divisional position distant regions of the side mold section, has lands defined by at least one circumferential groove which extends in a circumferential direction of the tire. Sipes which extend from the at least one circumferential groove into at least one of the lands with their extension ends located within the at least one land are disposed at predetermined intervals along the tire circumferential direction. The sipes comprise first sipes in the first regions and second sipes in the second regions. Each first sipe has a tire widthwise direction length W1 less than the tire widthwise direction length W2 of each second sipe.

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What is claimed is: 1. A pneumatic tire which is cured and molded by a sectional type tire mold including an annular side mold section having a tread forming surface for forming a tread surface, the side mold section comprising a plurality of sectors into which the side mold section is divided alon

What is claimed is: 1. A pneumatic tire which is cured and molded by a sectional type tire mold including an annular side mold section having a tread forming surface for forming a tread surface, the side mold section comprising a plurality of sectors into which the side mold section is divided along a circumferential direction of the side mold section, the tread forming surface of the side mold section having sector divisional position vicinity regions including sector divisional positions and sector divisional position distant regions located therebetween, the pneumatic tire having a tread surface which includes first regions formed by the sector divisional position vicinity regions, where the first regions extend along an entire axial width of the tread surface, and second regions formed by the sector divisional position distant regions, where the second regions extend along the entire axial width of the tread surface, the tread surface having lands defined by at least one circumferential groove which extends in a circumferential direction of the tire, sipes which extend from the at least one circumferential groove into at least one of the lands with their extension ends located within the at least one land being disposed at predetermined intervals along the tire circumferential direction, wherein the sipes comprise first sipes and second sipes, and each first sipe has a tire widthwise direction length W1 that is less than the tire widthwise direction length W2 of each second sipe, wherein the first sipes are disposed only in the first regions, and the second sipes are disposed only in the second regions, and further wherein said first region and said second region are alternately arranged in the circumferential direction of the tire, the first region being a region located between a position on the tread surface corresponding to the sector divisional position and a position ranging from 20 to 40 mm from said position corresponding to the sector divisional position on each side thereof in the circumferential direction of the tire. 2. A pneumatic tire according to claim 1, wherein the tire widthwise direction length W1 of each first sipe and the tire widthwise direction length W2 of each second sipe have the following relationship; description="In-line Formulae" end="lead"0.15×w2≦W1≦0.70×W 2.description="In-line Formulae" end="tail" 3. A pneumatic tire according to claim 1, wherein the first sipes are substantially equal in depth to the second sipes. 4. A pneumatic tire according to claim 1, wherein the at least one land has a sipe extension end wall surface located at an extension end of each first sipe and a sipe bottom surface located at a bottom of each first sipe, the sipe extension end wall surface being connected to the sipe bottom surface via a curved surface in the form of an circular arc in cross section having a radius R. 5. A pneumatic tire according to claim 4, wherein the radius R and the tire widthwise direction length W1 of each first sipe have the following relationship; description="In-line Formulae" end="lead"0.8×W1≦R≦1.5×W 1.description="In-line Formulae" end="tail" 6. A pneumatic tire according to claim 1, wherein each first sipe includes an extension end portion having edge portions on both sides thereof, at least one of the edge portions of each first sipe located on the remote side of the first sipe from a position in a first region of the tread surface where the first sipe is located having a chamfered shape, the position in a first region of the tread surface conforming to one of the sector divisional positions. 7. A pneumatic tire according to claim 1, wherein the at least one land has a groove side wall surface facing to the at least one circumferential groove and sipe side wall surfaces located on both sides of each first sipe, each first sipe having a sipe open part which is open to the groove side wall surface, sipe open end portions which face to the sipe open part being defined between the groove side wall surface and the sipe side wall surfaces, at least one of the sipe open end portions located on the remote side of the first sipe, from a position in a first region of the tread surface where the first sipe is located, being chamfered, the position in a first region of the tread surface conforming to one of the sector divisional positions. 8. A pneumatic tire according to claim 1, wherein the at least one land consists of a rib. 9. A pneumatic tire comprising: a tread surface having lands defined by at least one circumferential groove which extends in a circumferential direction of the tire; the tread surface being divided into a plurality of first regions and a plurality of second regions, wherein said first regions and said second regions are alternately circumferentially arranged around the tire, and further wherein said first regions and said second regions each extend from one axial edge of the tire to an opposite axial edge and an axially extending line extending from the one axial edge to the opposite axial edge defines adjacent edges of said first and second regions; a plurality of first sipes in each of the first regions; and a plurality of second sipes in each of the second regions, wherein each of said first sipes has a tire widthwise direction length that is less than a tire widthwise direction length of each of said second sipes, wherein sipes in each of said first regions include said first sipes without including any of said second sipes and further wherein each of said first regions extends approximately 40 to 80 mm in the circumferential direction of the tire. 10. The pneumatic tire according to claim 9, wherein sipes in each of said second regions include second sipes without any of said first sipes. 11. A tire mold including an annular side mold section having a tread forming surface for forming a tread surface of a tire, the side mold section comprising: a plurality of sectors into which the side mold section is divided along a circumferential direction of the side mold section, the tread forming surface of the side mold section having sector divisional position vicinity regions, extending along an entire axial width of the annular side mold section, including sector divisional positions and sector divisional position distant regions, extending along an entire axial width of the annular side mold section, located therebetween, each sector including a tread forming surface section, at least one circumferential groove forming ridge which extends in a circumferential direction of the side mold section and sipe forming blades which are connected to at least one side surface of the at least one circumferential groove forming ridge and extend from the at least one side surface of the at least one circumferential groove forming ridge in a widthwise direction of the side mold section protruding on the tread forming surface section of each sector, the sipe forming blades having extension ends which are located within the tread forming surface section of each sector and being disposed at predetermined intervals along the circumferential direction of the side mold section, wherein the sipe forming blades comprise first sipe forming blades and second sipe forming blades, and each first sipe forming blade has a side mold section widthwise direction length W'1 that is less than the side mold section widthwise direction length W'2 of each second sipe forming blade, wherein the first sipe forming blades are disposed only in the sector divisional position vicinity regions and the second sipe forming blades are disposed only in the sector divisional position distant regions, and further wherein said tread forming surface of said side mold section, said sector divisional position vicinity region and said sector divisional position distant region are alternately arranged in the circumferential direction of the tire, the sector divisional position vicinity region being a region located between the sector divisional position and a position ranging from 20 to 40 mm from said sector divisional position on each side of the sector divisional position in the circumferential direction of the side mold section. 12. A tire mold according to claim 11, wherein the side mold section widthwise direction length W'1 of each first sipe forming blade and the side mold section widthwise direction length W'2 of each second sipe forming blade have the following relationship; description="In-line Formulae" end="lead"0.15×w'2≦W'1≦0.70× W'2.description="In-line Formulae" end="tail" 13. A tire mold according to claim 11, wherein the first sipe forming blades are substantially equal in height to the second sipe forming blades. 14. A tire mold according to claim 11, wherein each first sipe forming blade has an extension end surface and a top surface connected thereto, a corner which is defined between the extension end surface and the top surface being chamfered with a curved surface in the form of an circular arc in cross section having a radius R'. 15. A tire mold according to claim 14, wherein the radius R' and the side mold section widthwise direction length W'1 of each first sipe forming blade have the following relationship; description="In-line Formulae" end="lead"0.8×W'1≦R'≦1.5×W' 1.description="In-line Formulae" end="tail" 16. A tire mold according to claim 11, wherein each first sipe forming blade includes side surfaces on both sides thereof and an extension end surface extending between the side surfaces, corners being defined between the extension end surface and the side surfaces, at least one of the corners, located on the remote side of the first sipe forming blade from a sector divisional position in a sector divisional position vicinity region where the first sipe forming blade is located, being chamfered. 17. A tire mold according to claim 11, wherein each first sipe forming blade has side surfaces on both sides thereof connected to the at least one side surface of the at least one circumferential groove forming ridge, corners being defined between the at least one side surface of the at least one circumferential groove forming ridge and the side surfaces on the both sides of the first sipe forming blade, at least one of the corners, located on the remote side of the first sipe forming blade from a sector divisional position in a sector divisional position vicinity region where the first sipe forming blade is located, being arranged so as to have a filled structure. 18. A tire mold including an annular side mold section having a tread forming surface for forming a tread surface of a tire, the side mold section comprising: a plurality of sectors into which the side mold section is divided along a circumferential direction of the side mold section; the tread forming surface being divided into a plurality of sector divisional position vicinity regions that include sector divisional positions and a plurality of sector divisional position distant regions located between said sector divisional position vicinity regions, wherein said sector divisional position vicinity regions and said sector divisional position distant regions each extend from one axial edge of the annual side mold section to an opposite axial edge; a plurality of first sipe forming blades in each of the sector divisional position vicinity regions; and a plurality of second sipe forming blades in each of the sector divisional position distant regions, wherein each of said first sipe forming blades has a side mold section widthwise direction length that is less than a side mold section widthwise direction length of each of said second sipe forming blades, wherein sipe forming blades in each of said sector divisional position vicinity regions include said first sipe forming blades without including any of said second sipe forming blades, and further wherein said tread forming surface of said side mold section, said sector divisional position vicinity region and said sector divisional position distant region are alternately arranged in the circumferential direction of the tire, the sector divisional position vicinity region being a region located between the sector divisional position and a position ranging from 20 to 40 mm from said sector divisional position on each side of the sector divisional position in the circumferential direction of the side mold section. 19. The tire mold according to claim 18, wherein sipe forming blades in each of said sector divisional position distant regions include second sipe forming blades without any of said first sipe forming blades.