Might as well go with the 275/40R18s to replace your original 245/45R18 size. They are the perfect size since they are within 0.1% of your original overall diameter.
You can also move your rear 245/45R18s to the front to replace your 225/50R18s. That's what I would suggest in order to make a meatier setup that matches the Sport package.
Why did you think you had to widen your wheels in order to install not much wider tires on them? There's many, many reasons I wouldn't recommend widening wheels...mainly safety, but other than that it also changes your offset to a more positive one (higher number) and it ruins your wheels and wastes your money.
