I'm scratching my head over the difference in the 18/19" wheel and 16" wheel speedometer drives. My '63 Scat has 18" wheels and the drive gear on the front hub has 23 teeth, and my '63 and '65 Pacers with 16" wheels has 21 teeth. All of them have the same 9 tooth driven gear. Is this correct? If you look at it terms of the math, it works out. The difference in revolutions per mile between the 16" and 18" wheels is about 8 %, and the difference in the drive's gear ratios (2.33:1 and 2.55:1) is about 9% so the readings would be correct. Can anyone confirm that the 9 tooth driven gear is correct for both the 21 and 23 tooth drive gear, or is there another driven gear?

Bob