Correcting Speedo after Wheel change.

excellent answers guys. Thank you so much for the help. I have no idea what the rear ratio is, but the method suggested by KosmicKuda seems like a great way to do it. I will try to get that figured out as soon as I figure out what is causing the sppedo clock to jump incessantly. I posted in another section, and have gotten a few good ideas. Once I get to the bottom of that, I will figure this little problem out. Thank you very much