Pneumatic tire

摘要

A pneumatic tire comprises a tread portion provided with a tread element provided with a pair of sipes. Each sipe comprises a radially outer constant width part and a widening part extending radially inwardly from the constant width part while gradually increasing the width of the sipe and then extending to the radially inner end of the sipe while gradually decreasing the width of the sipe. Each of the paired sipes has an inside sidewall surface positioned toward the other of the paired sipes and an outside sidewall surface positioned away from the other of the paired sipes. The inside sidewall surface includes an inside curved bottom surface having a radius of curvature Rib. The outside sidewall surface includes an outside curved bottom surface having a radius of curvature Rob more than the radius of curvature Rib.

主权项

1. A pneumatic tire comprising
a tread portion having a tread surface and provided with a plurality of ground contacting tread elements made of rubber, each of the ground contacting tread elements provided with at least one pair of sipes extending substantially parallel with each other, each of the sipes comprisinga constant width part having a constant width and extending radially inwardly from the tread surface anda widening part extending radially inwardly from the constant width part while gradually increasing the width of the sipe and then extending to the radially inner end of the sipe while gradually decreasing the width of the sipe,
each of the paired sipes havingan inside sidewall surface (11u) positioned toward the other of the paired sipes andan outside sidewall surface (11s) positioned away from the other of the paired sipes,
in the cross section of the sipe perpendicular to the longitudinal direction of the sipe, the outside sidewall surface in the widening part having an outside most protruding point (15) protruding toward the outside of the sipe and including an outside curved bottom surface (17) extending radially inwardly from the outside most protruding point toward the center line (6n) of the sipe while describing an arc, andthe inside sidewall surface in the widening part having an inside most protruding point (16) protruding toward the outside of the sipe and including an inside curved bottom surface (18) extending radially inwardly from the inside most protruding point (16) toward the center line (6n) of the sipe while describing an arc, wherein
the inside curved bottom surface has a radius of curvature Rib and the outside curved bottom surface has a radius of curvature Rob more than the radius of curvature Rib.