Gryphon =MPH

[nxtcsrt8]

my gryphon shows 2mph faster than my GPS. I have my tire size set to the manual specs and my gear ratio set correct. How do I change the settings to make my mph correct? Do I go up or down on tire size? I need to make my gryphon read 2mph slower.
Alan

[ticopowell]

Do a quick search to verify what I remember, but I think that with a smaller number inputted(tire size), the displayed speed goes down. so put a larger tire size in the gryphon and see what happens, Try to do it a couple percentage at a time and see how that changes.
Did you account for squish? usually a 3% reduction in tire size is calculated so subtract 3% if you havent and see how that works for ya.
Hope this helps.

[Jackpine]

I agree with everything except the direction of the tire size change. To make the Gryphon (and your dashboard speedo) read slower, which is what I think you want, you need to reduce the Tire Size. The 2 mph difference is probably about the 3% that ticopowell mentioned that compensates for "squish". Try multiplying your current Tire Size by 0.97 and use that result as your TS.

Remember, when you get your Gryphon and GPS to agree, the dash speedo will still read about 2 mph high at 70 mph due to mechanical errors. But, the odometer will be correct.

- Jack