There are some references to the circumference of an NBA basketball; however, there is nothing about circumference in the rules. NBA only lists the pressure in the rules governing equipment.
Official Rules of the National Basketball Association
Rule No. 1—Court Dimensions–Equipment
Section II—Equipment
f. (1) The ball shall be an officially approved NBA ball between 7 ½ and 8 ½ pounds pressure.
(2) A minimum of nine balls must be made available to each team for pre-game warmup.
References:
Official Rules of the NBA – https://official.nba.com/rule-no-1-court-dimensions-equipment/
Photo – www.matchwinner.co.uk/ball-pressure-gauge.html
