Pneumatic tire

Abstract

Provided is a pneumatic tire having at least one carcass layer as a skeleton extending in toroidal shape over a pair of bead portions, at least one belt layer and a tread disposed on an outer side in the radial direction of a crown portion of the carcass. In a tire section in the widthwise direction in state where the tire is assembled to an application rim, ratio BD/BW of radius difference BD between radius at a center portion and radius at an end portion in the widthwise direction of an innermost layer of the belt layer, to width BW of the innermost layer, ranges from 0.01 to 0.04, and ratio TD/TW of radius difference TD between radius at a center portion and radius at an end portion of the tread in the widthwise direction of a tread ground surface, to tread ground-contact width TW, satisfies BD/BW<TD/TW.

1 . A pneumatic tire having at least one carcass layer as a skeleton extending in a toroidal shape over a pair of bead portions, at least one belt layer and a tread that are disposed on an outer side in a tire radial direction of a crown portion of the carcass layer, wherein
 in a section of the tire in a tire widthwise direction in a state where the tire is assembled to an application rim,   a ratio BD/BW of radius difference BD between radius at a center portion and radius at an end portion in the tire widthwise direction of an innermost layer of the belt layer, to a width BW of the innermost layer, is in the range of 0.01 to 0.04, and   a ratio TD/TW of radius difference TD between radius at a center portion and radius at an end portion of the tread in the tire widthwise direction of a tread ground surface, to a tread ground-contact width TW, satisfies the relation BD/BW<TD/TW.   
     
     
         2 . The pneumatic tire according to  claim 1 , wherein
 a ratio TGh/TGc of a tread gauge TGh measured in a tread end portion, to a tread gauge TGc measured in a tread center portion, is in the range of 0.5 to 0.9, and   a ratio TGe/TGc of a tread gauge TGe measured in the end portion in the tire widthwise direction of the innermost layer to a tread gauge TGc measured in the tread center portion is in the range of 0.2 to 0.6.   
     
     
         3 . The pneumatic tire according to  claim 1 , wherein
 a ratio CSWh/CSH of a shortest distance CSWh between a line drawn in parallel with a rotation axis of the tire at a maximum width position of the carcass and a line drawn in parallel with the rotation axis of the tire at a bead toe, to a distance CSH in the tire radial direction between an outermost side of the carcass in the tire radial direction and the bead toe, is in the range of 0.6 to 0.9.   
     
     
         4 . The pneumatic tire according to  claim 1 , wherein
 a ratio SWh/SH of a shortest distance SWh between a line drawn in parallel with the rotation axis of the tire at a maximum width position of the tire and a line drawn in parallel with the rotation axis of the tire at the bead toe, to a sectional height SH of the tire, is in the range of 0.5 to 0.8.   
     
     
         5 . The pneumatic tire according to  claim 1 , wherein
 a ratio BW/CSW of the width BW of the innermost layer, to a maximum width CSW of the carcass, is in the range of 0.8 to 0.94.   
     
     
         6 . The pneumatic tire according to  claim 1 , wherein
 a ratio CSL/CSP of a path length CSL from a position corresponding to the end portion in the tire widthwise direction of the innermost layer to a position corresponding to the maximum width position of the carcass, to a path length CSP from a position corresponding to the center portion in the tire widthwise direction of the innermost layer to a position right below a bead core, is in the range of 0.1 to 0.25.   
     
     
         7 . The pneumatic tire according to  claim 1 , wherein
 a shortest distance CSEh between a terminal end of a turn-up portion of at least one carcass ply layer and a line drawn in parallel with the rotation axis of the tire at the bead toe is greater than the shortest distance SWh.