Hi Tom, There are a few variables here that would need to be addressed. You need to verify that your speedometer is correct. The easiest way to do that would be with gps. That RPM sounds high. My G would be doing an indicated 75-80 at 3,000. I can't believe there would be that much difference between 14 and 15 inch wheels. The next thing would be to confirm that the tach is correct. This can be done easy enough with a tach/dwell meter. Then you would have to check the rear end ratio. Using the calculator that someone else mentioned would be the easiest way. 300ly, Don ----- Original Message ----- From: Thomas Cox To: chrysler300@xxxxxxxxxxxxxxx Sent: Thursday, August 25, 2011 7:48 PM Subject: [Chrysler300] Rear End 300F At 60 mph, I am running about 3,000 rpm. Is this to be expected with a 3.23 rear end? I wonder if I have the correct "chunk" in the F rear end. [Non-text portions of this message have been removed] [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: Chrysler300-digest@xxxxxxxxxxxxxxx Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/