Quote:
It must have been calibrated before you bought it then. No stock sierra speedo will read only 4-6k's out with 31's as they are just over 15% larger in diameter.
There is a lever on the back of the sierra speedo that you can move up and down to change where the needle sits at certain speeds. it is not the best nor the most accurate way to change a speedo, but it does work. Maybe they fiddled with that before he turned it over.