A golf ball 2 includes a core 4 , one or more mid layers 6 , a cover 8 , and dimples 10 . A central hardness Ho and a surface hardness Hs of the core 4 , a hardness Hm(min) of a layer having a lowest hardness among the mid layers 6 , and a hardness Hc of the cover 8 satisfy the following mathematical formulas (1) to (4). Hs−Ho >15 (1) Hc−Hm (min)>20 (2) −10< Hm (min)− Ho <15 (3) 5< Hc−Hs <20 (4) An occupation ratio So and a ratio Rs of a number of the dimples 10 each having a diameter of from 9.60% to 10.37% of a diameter of the golf ball 2 , relative to a total number of the dimples 10 , satisfy the following mathematical formula (5). Rs ≥−2.5* So +273 (5).
1. A golf ball comprising a core, one or more mid layers positioned outside the core, and a cover positioned outside the mid layers, wherein
a Shore C hardness Ho at a central point of the core, a Shore C hardness Hs at a surface of the core, a Shore C hardness Hm(min) of a layer having a lowest hardness among the mid layers, and a Shore C hardness Hc of the cover satisfy the following mathematical formulas (1) to (4),
Hs−Ho> 15 (1),
Hc−Hm (min)>20 (2),
−10< Hm (min)− Ho< 15 (3), and
5< Hc−Hs< 20 (4),
the hardness Hc of the cover is higher than a Shore C hardness Hm(max) of a layer having a highest hardness among the mid layers,
the golf ball has a plurality of dimples on a surface thereof,
a ratio So of a sum of areas of the dimples relative to a surface area of a phantom sphere of the golf ball is not less than 81.0%,
a ratio Rs of a number of the dimples each having a diameter of not less than 9.60% and not greater than 10.37% of a diameter of the golf ball, relative to a total number of the dimples, is not less than 50%,
a dimple pattern of each hemisphere of the phantom sphere includes three units that are rotationally symmetrical to each other,
a dimple pattern of each unit includes two small units that are mirror-symmetrical to each other, and
the golf ball satisfies the following mathematical formula (5):
Rs≥− 2.5* So+ 273 (5),
wherein
a ratio Rs′ of a number of the dimples each having a diameter of not less than 10.10% and not greater than 10.37% of the diameter of the golf ball, relative to the total number of the dimples, is not less than 50%, and
the golf ball satisfies the following mathematical formula (8):
Rs′≥− 2.2* So+ 245 (8).
2. The golf ball according to claim 1 , wherein a sum of a thickness of the cover and thicknesses of all the mid layers is not greater than 2.8 mm.
3. The golf ball according to claim 1 , wherein the golf ball satisfies the following mathematical formula (6):
Rs ≥−2.5* So+ 278 (6).
4. The golf ball according to claim 3 , wherein the golf ball satisfies the following mathematical formula (7):
Rs≥− 2.5* So+ 283 (7).
5. The golf ball according to claim 1 , wherein the golf ball satisfies the following mathematical formula (9):
Rs′≥− 2.2* So+ 252 (9).
6. The golf ball according to claim 1 , wherein a depth of a deepest part of each dimple from a surface of the phantom sphere is not less than 0.10 mm and not greater than 0.65 mm.
7. The golf ball according to claim 1 , wherein a total volume of the dimples is not less than 450 mm 3 and not greater than 750 mm 3 .
8. The golf ball according to claim 1 , wherein
the Shore C hardness Ho at the central point of the core is not less than 40 and not greater than 60, and
the Shore C hardness Hs at the surface of the core is not less than 70 and not greater than 90.
9. The golf ball according to claim 1 , wherein a difference (Hc−Hm(max)) between the hardness He of the cover and the Shore C hardness Hm(max) of the layer having the highest hardness among the mid layers is not less than 5 and not greater than 45.