so how do i do it exactly?

To understand the custom option menu read this.
http://forum.gopowerhungry.com/faqs-....html#post9248
Your tires 285/55R22
Calculate to 2740mm
With 3.5% squish taken out is.
(2644mm) try this number.
The gryphon uses millimeters.
Also make sure to use the right gear ratio.
Hope this helps.

Peace!:)