Huh? Your calculation of the number of revolutions the tire goes through in a mile is way off. You used the diameter of the tire in the place of the circumference. The circumference of a 23.23" diameter tire is 72.97". Thus the revolutions per mile of the tire = 63,360" / 72.97 =~ 868.3 revolutions per mile. However, that assumes that there is a 1:1 gear ratio between the wheel and the speedo cable (that the speedo cable spins 1 revolution for every 1 revolution of the tire). Is this the case? Regards, Jon Heese Bruce Benson wrote: > The 195/60/14 tire is 23.23" in diameter. A mile = 5,280 feet x 12"= 63360" > . Divide that by the tire's 23.23" = 2727.5 revolutions per mile. 60 mph is > a mile a minute so at 60mph the speedo gear is turning 2727.5 rpms. > > Bruce Benson > > _______________________________________________________________________ > > >> 6a. Speedo gear rpm. >> Posted by: "Bob Brandys" BobB@xxxxxxxxxxxxxx bob6351 >> Date: Sun May 4, 2008 5:24 pm ((PDT)) >> >> Does anyone know what RPM the speedo cable operates at? >> >> Bob >> >> >> >> Messages in this topic (4) >> ________________________________________________________________________ ------------------------------------ To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnewsYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/