From my info, 11" wouldn't fit unless it's got a very obscure offset and you do some major modifications. You might get away with it if you had a stretched tyre, but running a tyre that's designed for the 11" rim will almost certainly cause issues, with the minimum problem of the sliding door catching the tyre.
Personally i've run 10" twice, but without my tyres being stretched on my 20" alloys, it would of hit the rear arches, but my 10" banded RR sat pretty well on a none stretched tyre.
I'd love to go much wider at the rear, 11" or even 12" with a really wide low profile tyre. That would look awesome from behind.
(way too many puns in my answer, so before anyone takes any of my words and trims them out of context, i'm watching you)