Looking into the feasibly of using a 12.5in rear in 2020, the tire options are extremely limited. I also don't want to get too far off the rolling diameter or the TCS will start having issues. Historically, people used 355/25-19, but these tires are NLA, with only used tires with "vintage" date codes remaining. No 355, 345, 335, or 325/25-19 are available new per tirerack (as of 8/2020) Some digging around shows you can still get a 325/30-19, but recall factory is a 305/30-19. I am not sure if the TCS will like the added sidewall? It appears 325 are also rated for up to 12, not 12.5in wheels, at least for the michellin and bridgestone offerings. What are people running (if anyone is even still running anything this wide)?