Hey ZForce,
I think you will be fine with the 255 and those spacers up front. There's plenty of room in those fenders. I would even go 265/285. I think thats a great combo for the car. Someone had the 265/305 combo on their stock wheels and spacers, but you're gonna have to look it up. Not sure who it was...maybe repipsa?
Try and get as much tire under the front fenders as possible, this car tends to understeer when you start playing around with bigger rears and grippier tires.
I have 265/305 right now and haven't had a chance to really put them to the test yet
