Changing tire size

[Slopjock78]

Ok, so I've got a fairly simple question, and I probably could have found the answer if I would have looked a little harder.....

anyhow, I just sent in my Gryphon yesterday to be reprogrammed from a 5.4L gas to a 6.4L diesel. My question is this: i have put on bigger sized tires then stock, can I personally change the tire size once I get the unit back? i was always under the impression that i could, but wanted to make sure.

thanks for the help
slopjock78