With a low profile tire I think it is even more critical to stay within the range. There just isnt that much sidewall there to perform the transition.
I'm running into similar problem while shopping for wheels and tires too. Unless you can spring for a uber pimp forged wheel it is hard to find many at 10" width. Who wants to spend the time and money on a minitub and put a 285 tire in there on the 9.5" wheel. Vintage Wheel Works now has an 18X11 wheel out though. Problem then is tires. Seems limited in the 305/35 - 315/35 range for 18" wheels. Oh the joys of project cars
