Personally I would lean toward the 255's on a 9" rim especially on the front. A nearly 11" wide tire is going to be bulgy on the rim and allow a lot of movement. if you can get 10" rims on there, yeah I can see the 275s working, its worth a test anyways.
This was a very tight autox test course 225/45/17 17x8. Sorry for the weird angle. You can see that in the tight 360 the entire car is on the very edge of the shoulder.
