Gryphon won't correct tire size

[btownford]

I had custom tunes by PHP, but my computer was reflashed 2° new motor being installed. I have an 05 F-150 with a 06 motor. I updated my gryphon to the canned tunes offered through Pegasus. I install in truck and every is a go except for the tire correction. I have 285/70/17 and inputed 2610 and hit enter. i check back before programming and it saved my tire input mm. When i go to program my speedometer is 7mph fast according to GPS. When I go back to reprogram truck I load previous settings and everything loads except for the tire size and it reverts back to 2356mm or whatever. I tried it atleast 4 times without success. I updated to the newest firmware and calibrations prior to tuning everything.

Anybody have a clue why its not doing my tire size correctly?