Thanks to all that replied to to my question. Each reply added to the final answer. The .469" diameter converted to millimeters is 11.9 mm. I counted the threads on a 1/2" section of the thread and it came out to 13, multiplied by 2 = 26 TPI.
Checking the Ebay auction site showed a 12mm X 26 tap size as one of the 3 taps available for these tire valves. Thanks again, Frank Duval, Cudaman, viv w, 30DodgePanel and Dandy Dave