I just rechecked and you'll have to disregard it. The air boxxer likes to sit into its travel 5mm or more at lower pressures it seems, hard to get an accurate A-C measurement. I'm pretty sure the rockshox official figure is 568mm though (can someone confirm)?
But mine is as low as it'll go (wipers are 1-2mm from crown at bottom out) and nowhere near tyre contact from what I could see, so your limiting factor will probably just be the crown/wipers I reckon. I'm running maxxis minion 2.5.
yes i think its 568 that gives you 203mm stanchion clearance, or at least very close. they come stock that way btw.