| 摘要 |
A pneumatic tire having on-snow performance improved by increasing traction performance on snow-covered road with maintaining dry grip performance high, and comprising tread surface 2 having at least one circumferential main groove 3 in an outer region 2o facing outward of a vehicle, the circumferential main groove 3 being a straight groove wherein ridge lines 21 at which groove wall surfaces 20 intersect with the tread surface 2 extend straight, each groove wall surface 20 comprising a gently-inclined upper wall surface 20U extending from the ridge line 21 at an angle &thetas;1 of 40 to 60° with respect to a normal line to tread surface 2 and a steeply-inclined lower wall surface 20L extending to groove bottom 22 at an angle &thetas;2 smaller than the angle &thetas;1, and the lower wall surface 20L including projections 23 which are disposed at intervals in the circumferential direction and have a triangular cross section with slope surface 23S extending from lower end Ue of the upper wall surface 20U to groove bottom 22 at an angle &thetas;3 which is not greater than the angle &thetas;1 but is greater than the angle &thetas;2.
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