Many thanksL.A.B.The primary chain is 3/8" (0.375") pitch.
For example, 16 pitches of a new 3/8" pitch chain (0.375 x 16) is exactly 6 inches.
24 = 9 inches
32 = 12 inches.
http://www.sprocketsunlimited.com/Chainmaintenance.html
"For a 3/8" pitch chain, 24 pitches of a new chain will come to the 9 inch mark of the rule and the limit for wear would be 9.192 inches for 24 pitches."