Pneumatic Tire

Abstract

A pneumatic tire is provided with, in the tread surface, land portions that include a plurality of blocks. The land portions are provided with a plurality of narrow shallow grooves and a plurality of recessed portions in a contact patch. The opening area ratio Se′ of the recessed portions in the end portion regions in the tire circumferential direction of one continuous contact patch and the opening area ratio Sc′ of the recessed portions in the central portion region in the tire circumferential direction have the relationship Sc′<Se′, where the central portion region is defined as the region in the central portion in the tire circumferential direction occupying 50% of the continuous contact patch, and the end portion regions are defined as the regions in the front and back end portions in the tire circumferential direction occupying 25%.

1 . A pneumatic tire comprising in a tread surface thereof a land portion that comprises a plurality of blocks,
 the land portion comprising in a contact patch thereof a plurality of narrow shallow grooves and a plurality of recessed portions, and   an opening area ratio Se′ of the recessed portions in end portion regions in a tire circumferential direction of one continuous contact patch and an opening area ratio Sc′ of the recessed portions in a central portion region in the tire circumferential direction having a relationship Sc′<Se′, where   the central portion region is defined as a region in a central portion in the tire circumferential direction occupying 50% of the continuous contact patch, and the end portion regions are defined as regions in front and back end portions in the tire circumferential direction occupying 25%.   
     
     
         2 . The pneumatic tire according to  claim 1 , wherein the opening area ratio Se′ of the recessed portions in the end portion regions in the tire circumferential direction and the opening area ratio Sc′ of the recessed portions in the central portion region in the tire circumferential direction have a relationship 1.50≤Se′/Sc′. 
     
     
         3 . The pneumatic tire according to  claim 1 ,
 wherein a disposal number Ne′ of the recessed portions in the end portion regions in the tire circumferential direction and a disposal number Nc′ of the recessed portions in the central portion region in the tire circumferential direction have a relationship Nc′<Ne′.   
     
     
         4 . The pneumatic tire according to  claim 3 , wherein the disposal number Ne′ of the recessed portions in the end portion regions in the tire circumferential direction and the disposal number Nc′ of the recessed portions in the central portion region in the tire circumferential direction have a relationship 1.50≤Ne′/Nc′. 
     
     
         5 . The pneumatic tire according to  claim 1 , wherein a disposal density Da of the recessed portions in an entire region of the one continuous contact patch is in a range 0.8 unit/cm 2 ≤Da≤4.0 unit/cm 2 . 
     
     
         6 . The pneumatic tire according to  claim 1 , wherein
 the land portion comprises in the contact patch thereof a plurality of sipes, and   the recessed portions are disposed spaced apart from the sipes.   
     
     
         7 . The pneumatic tire according to  claim 1 , wherein
 the land portion is a row of blocks that comprises a plurality of blocks, and   the recessed portions are disposed in corner portions of the blocks.   
     
     
         8 . The pneumatic tire according to  claim 1 , wherein the opening area of the recessed portions ranges from 2.5 mm 2  to 10 mm 2 . 
     
     
         9 . The pneumatic tire according to  claim 1  wherein the recessed portions have a circular or elliptical shape at the contact patch of the land portion. 
     
     
         10 . The pneumatic tire according to  claim 1 , wherein a wall angle α of the recessed portions is in a range −85 degrees≤α≤95 degrees. 
     
     
         11 . The pneumatic tire according to  claim 1 , wherein a depth Hd of the recessed portions and a groove depth Hg of the narrow shallow grooves have a relationship 0.5≤Hd/Hg≤1.5. 
     
     
         12 . The pneumatic tire according to  claim 1 , wherein at least one of the recessed portions is disposed at a position corresponding to a vent hole of a tire mold. 
     
     
         13 . The pneumatic tire according to  claim 1 , wherein an average value Ae′ of the opening area of the recessed portions in the end portion regions in the tire circumferential direction and an average value Ac′ of the opening area of the recessed portions in the central portion region in the tire circumferential direction have a relationship Ac′<Ae′. 
     
     
         14 . The pneumatic tire according to  claim 13 , wherein the average value Ae of the opening area of the recessed portions in the end portion regions in the tire circumferential direction and the average value Ac of the opening area of the recessed portions in the central portion region in the tire circumferential direction have a relationship 1.5≤Ae′/Ac′≤4.0. 
     
     
         15 . The pneumatic tire according to  claim 13 , wherein
 the land portion comprises a plurality of types of the recessed portions with differing opening areas, and   70% or more of the recessed portions disposed in the end portion regions in the tire circumferential direction have a larger opening area than an average value of the opening area of the recessed portions disposed in the continuous contact patch.   
     
     
         16 . The pneumatic tire according to  claim 13 , wherein
 the land portion comprises a plurality of types of the recessed portions with differing opening areas, and   the recessed portions with an opening area larger than the average value of the opening area of the recessed portions disposed in the continuous contact patch are disposed on an outermost side of the continuous contact patch in the tire circumferential direction.