I'd be curious to know if Cam actually typed that writeup. That rear tire size yields 26.7 inch overall diameter, almost two full inches more than oem. Don't believe everything you read on the internets
Those wheels arent wide enough, and with that much overhang (ie a wider tire on a thin wheel) and that much sidewall, you're squeezing the wrong kind of rubber (height) in there. I can't think of one good reason to do it. There is, however, a reason FD road race guys have been running 285/30-18 on 10 inch wheels at each corner for many years now.
While those wheels are cheap, how much do they weigh? RPF1s aren't much more, and are very light.