Inside Diameter US UK Germany Spain France Italy
14 mm 3 F 44 (14.0) 4 44 4
15 mm 4 H 47 (15.0) 6,5 46.5 7
15.6 mm 5 J 49 (15.6) 9,5 49.5 9
16.6 mm 6 L 52 (16.6) 12 52 11
17.2 mm 7 N 54 (17.2) 14,5 54.5 14
18.1 mm 8 P 57 (18.1) 17 57 16