2015 Charger 3.6

[Redstripe]

I've been playing with 0-60 runs since getting trinity, dianlo tunes, and overkill tunes. Is it common place for people to adjust their parameters for tire size? Both diablo and overkill preset parameters do not match my tire size, just wondering. Prior to changing it on overkill 91 tune, my best time 0-60 was 6 flat. Now i'm in mid/high 5s with the same tune. 93 on both diablo and overkill dont seem as great but I also noticed the gas station I use had "could contain 10% ethanol" on 93 pump, could this effect 93 tunes?
Lastly, I have a platinum service package with dodge, do i need to swap out my pcm with stock one prior to service? Not sure on liklihood of voiding any warranty but I rather be safe than sorry, plus the swap is too easy so thought i'd ask. Thanks in advance.