Sumitomo Rubber Industries Limited

Yukari Tomisaki

Ryoji Kojima

Takuya Horiguchi

Tsuyoshi Tsuchida

Shoko Nakahata

Yogun Kida

Ayaka Kitaou

Kanako Hata

Naoyuki Miki

Provided is a pneumatic radial tire for a passenger car that exhibits both riding comfort at low temperatures and stealing stability at high-speed running. The present invention is a pneumatic radial tire for a passenger car, in which: a carcass and a tread are provided; the tread is integrated into a standardized rim; when internal pressure is at a standardized internal pressure, the tire has a cross-sectional width Wt (mm) and an outer diameter Dt (mm) satisfying 1963.4≤(Dtπ/4)/Wt≤2827.4; the tread comprises at least one main groove in a running surface of the tread, extending in the circumferential direction of the tread; the land/sea ratio at the tread running surface is greater than 55% and less than 85%; and a rubber composition that forms the tread has a loss tangent (tan δ) which, when measured at a frequency of 10 Hz, an initial strain of 2%, and a dynamic strain rate of 1%, is such that |20° C. tan δ-50° C. tan δ| is at least 0.01 and less than 0.15, and |5° C. tan δ-20° C. tan δ| is greater than 0.15 and less than 0.70.

Pneumatic radial tire for passenger cars

A pneumatic tire comprising a tread composed of a rubber composition containing 30 to 120 parts by mass of silica having a BET specific surface area of 180 to 280 m/g based on 100 parts by mass of a rubber component, wherein, under a normal state with no load where the pneumatic tire is mounted with a normal rim and filled with a normal internal pressure, a grounding surface shape in which a normal load is applied and the tread is pressed against a plane surface satisfies the following equation (1): 0.95&#x2264;SL0/SL80&#x2264;1.6 (wherein, SL0 is a ground contact length in a circumferential direction of the tire on a tire equator, and SL80 is a ground contact length in a circumferential direction of the tire on a position away from the tire equator by a distance in a tire axial direction of 80% of a tread grounding half width.)

Pneumatic tire

Provided are a polymer ready for introduction into a kneading machine which is milled with good milling efficiency in a kneading machine and which provides a kneaded mixture with excellent filler dispersion, and a rubber composition and a pneumatic tire containing the polymer. The present invention relates to a polymer ready for introduction into a kneading machine, excluding natural rubber, the polymer having a temperature within the range of &#x2212;20&#xb0; C. to 80&#xb0; C. and satisfying the following formula (I):(Tip clearanceof kneading machine)&#x2264;(Volumeof polymer ready for introduction into kneading machine)&#x2264;2.0&#xd7;10cm&#x2003;&#x2003;(I).

Method for kneading a polymer

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Hyogo, Japan

Yukari Tomisaki