Mahalo to blackfx4ny, Jackand Janet, and Bill for all of the information. I'll use the the figures that you guys provided and go from there. I'll contact my sister-in-law and see if I can borrow her GPS to try and get an accurate tire size. By the way, after I posted the thread, I installed the Gryphon. The instructions very were easy to follow. Went out for a short drive using level 2. All I can say is WOW!!!!
What a difference. Makes me anxious to know what the custom tune will do to the truck. Corey and Bill, mahalo for the great product and service.