| 摘要 |
PURPOSE: A pneumatic radial tire is provided to make a third circular arc of the tire forming a tread profile into a straight line of an infinite curvature radius with a minimum flatness and three circular arcs and to obtain an optimal tread. CONSTITUTION: An in-mold for a radial tire for a vehicle has a minimum flatness of 30¯55 and forms a tread profile with first, second, and third circular arcs(TW1,TW2,TW3). The length of the second circular arc forming the curvature of a tread(7) having a symmetrical profile at a section of a pneumatic pressure non-applied tire is 1.0¯2.0 times as long as the length of the first circular arc. The length of the third circular arc is below 0.75 times of the second circular arc. A first curvature radius(TR1) of the first circular arc is within 1.5¯2.5 times of a second curvature radius(TR2) of the second circular arc. A third curvature radius(TR3) of the third circular arc is infinite.
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