Bones, you divide the number of teeth on the rear by the number of teeth on the front to get your final drive ratio. On my xrl for example, stock is 15-45, 45 divided by 15 is 3. I run 14-49, for 3.5 but I don't do much highway. I used to run 15-53 on my old xl600, it's almost the same ratio as 14-4...