Right, and Toyota says to never have more than 1 degree of negative camber on the front of my MR2.

Manufacturers are providing specs based on the general public, not us with special applications.

You can put a 225 on a 5" wheel, and you can put a 275 on an 8" wheel. Your tire guy will not like you and No, it's not ideal, but it fits, and the more tire you have, the more traction you have. And Mustangs need all the damn mechanical grip they can get, because their suspension isn't trying to help, it's trying to hurt you.