Diameter (MM)

Circumference (MM)

US / CAD / MEX

UK / AUS

EU

Asia / South America

15.7

49.32

5

J ½

49

50

9

16.5

51.87

6

L ½ 

M

52

11

12

17.3

54.51

7

N ½

O

54

55

14

18.2

57.15

8

P ½

Q

57

16

18.9

59.34

9

R ½

59

60

18