I installed the speedohealer, but the online tool keeps giving me the wrong #s. I went from stock gears 16, 43 to 15, 45 and now my speedo reads way to low. Can someone please tell me what I'm doing wrong. thanks. or the # they used.

 

The easiest and best method is to use a GPS to pace your speed. If you don't have a GPS, just blow by a cop at 70 in a 25 mph. When he asks you "do you know how fast you were going?" That'll give you the numbers you need.

Ok, the cop thing is a joke, but you can pace with a car that you know is accurate. One that is factory and doesn't have aftermarket wheels or tires on it. PM me if you have any questions.