Manga_Spawn

Front should be 215 or 225 40 18. Rears are 255/35/17. The second number in a tire size is a percentage of the first number. The second number (aspect ratio) is lowered as the tire is widened to try and keep the overall diameter the same as the narrower tire.

Those offsets are pretty bad and as other said just throwing on wider tires is risky. I hope that the fenders are at least rolled. The silver car you posted the picture of had the front fenders worked by a body shop to allow for more room. They aren't just rolled fenders.

I would go with 215/40/18 fronts and 245/35/18 rears. They will still look a little stretched but it'll give you more room but this is assuming the fenders are rolled. If they aren't you have to address that before worrying about anything else.

RedCelica

225/40/18 is your answer. Now let's hope you don't have to roll more to fit them!

indys2kautocrosser

I have 265/35/18 on the rear of my car for autocross. However I am still running on the stock springs and shocks. There is no issues with the width and when I autocross nothing ever rubs. Occasionally when I go over a high speed large dip on the highway it will lightly rub but that is rare.
If your car has been lowered it will probably be more of an issue. I would go with 17's if you want to keep it lowered. I never have any issue with my fronts at 225/40/18.
I also have the stock width still. 7' up front and 8.5" in rear.