You know I saw a 275/30/19 front and 293/30/19 rear setup on a ZCP car and the sidewall didn't look pinched at all. Although I do generally agree that a 275 width tire needs a 9.5" width tire, I don't think it would make that much of a difference.
2013 M3 Coupe-MR/BLK ZCP, identical to my 2011.
2011 M3 Coupe-MR/Blk
2007 Porsche 997C2S Speed Yellow/Blk sport seats
2004 BMW M3 Imola/Blk