Can O' worms, indeed!
I'm not good with tech to start with so I fully admit I may have been the issue, but I managed to get the seatbelt chime turned off (a big accomplishment in a 24'), fogs and high beams to stay on together, programmed a new key fob and activated the key in the vehicle security lock-out feature. I followed the process and succeeded with those, but the tire change just wouldn't work on my truck. I googled and found more than enough people having similar experiences to make me suspect there's something above simply following the process incorrectly going on. I can adjust the tire size all day long without issue, but the second I try to program it over a 34" tire, it flipped out.
With Jscan I was not able to get it to revert to factory settings. I kept getting a message saying it had, but I'd wait the adaptation period and the problems hadn't resolved. I downloaded AlphaOBD and managed to get the size back to the factory setting and no more dash lights.