I've made some spreadsheets and put them on my site. Most are related to Land Speed Racing, but the transmission gear ratio ones might be of some interest. You can download the one that matches your transmission type (3 speed, 4 speed, etc.) and put in the rearend ratio and tire diameter and see the rpm's at different speeds. This way you can see what changing rear gears or tire sizes will do for you. Even if you don't know the internal gear ratios of your transmission you can set up the final one for 1:1 or Overdrive and look at your speeds there. You can find them all ( HERE ). Let me know if you find any mistakes or if you have any questions. c ya, Sum