US Size

Inside Diameter

Inside Circumference

7

17.35mm

/ 0.68 in

55mm

/ 2.17 in

8

18.19mm

/ 0.72 in

57mm

/ 2.24 in

9

18.89mm

/ 0.74 in

59mm

/ 2.32 in

10

19.84mm

/ 0.78 in

62mm

/ 2.44 in

11

20.68mm

/ 0.81 in

65mm

/ 2.56 in

12

21.49mm

/ 0.85 in

68mm

/ 2.68 in

13

22.33mm

/ 0.88 in

70mm

/ 2.76 in