Are What RPMS should a /6 be at while driving 55?

Here is a calculater.

You need to know,
Your what gears you have in the rear.
Your rear tire higth from the ground to the center of the tire.
ie,26' tall tire would be 13'

divide your tire higth by your gear ratio times RPM divided by 168.


Example.

(13) divided by (3.23) times (3000rpm) divided by 168=71.87MPR@3000rpm


You can put in any RPM you want to see what MPH you are runing at that RPM. The 168 is a constint for a 1 to 1 ratio and must stay the same

Hope that helps.