Brain PFART. The ratio of the diameter to the circumference is pixd. Since pi is 22/7 or 3.14, the parts of the rollers that touch will not be per the diameter ratio but that ratio with respect to pi.
I have to go to town right this minute and will return later today. If this thread is still up, I'll do the correct calculation on the gear ratio.
Sorry for the error. The longer you're retired, the more that slips your mind.