Tire circumference getting changed by Gryphon

[tmsbandman]

Hi all. I decided to try a different tune, and even though I hit "load previous settings" my tire size got wiped. I think the default is 2356. I tried to put in values several times, but then when I go back to is (via load previous settings) it was defaulted back again. I know that I read here that the tire size setting is actually a "revolutions per mile" setting. Can anyone tell me where the "notches" are in the available settings? That way I can save a little frustration. Right now it's at 2691, which is a little big for my 275/60/20 tires. If I can know the built in increments on the Gryphon, it would help. Seems like maybe 2591 may have been my value that worked before.

Thanks