Arif Posted October 29, 2002 Share Posted October 29, 2002 I have done many mods to my Z car and it has just hit me that my speedo has to be way off. I originally had 195/70/15 wheels and a 3.54 diff. The new set-up consists of 225/50/15 tires and a 3.7 diff. How far off is my speedo now? When I upgrade to 17" rims what size tires do I need in order to correct my speedo reading? Thanks Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 30, 2002 Share Posted October 30, 2002 web page you may need the white 19 tooth speedometer cog for the 3.90 diff.Check the above webpage out, then figure out the diameter of your new tires to add in on which of the 5 cogs you need from Nissan Quote Link to comment Share on other sites More sharing options...
dmanzo57 Posted November 1, 2002 Share Posted November 1, 2002 Here's the formula I used to figure out which speedo gears I needed to recalibrate my speedo after changing rear end gears and tire sizes... Note: Drive gear refers to the gear that is on the transmission output shaft. The driven gear is located in a removable housing usually in the tailhousing of the transmission. # Drive Teeth X Axle Ratio X Tire Rev. per Mile ---------------------------------- = # Driven Teeth 1024 Use the following formula to calculate the Tire Rev. per Mile for the above formula. 20168 ---------------- = Tire Rev. per Mile Tire Diameter (inches) Don Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.