Agreed. 215/45/17 is what I run on my car on a 7" rim. I always try to fit the widest tire within reason. Some sizes are harder to come by, and I always check the overall diameter of the tire in Tire Rack's specs to insure I'm not going to have speedometer discrepancies.
I'm not sure about 225/40/17s- that size might be correct also- or within reason. Just checked: Those are competition only tires, with only Hoosier making a tire that size from Tire Rack. 225/45/17 is more common, and has a 25" overall diameter as compared to the 24.7" diameter of 215s. You'd be going slightly faster than your speedo said you were going, and if the suspension was lowered you'd want to make sure you were rubbing with factory snubber height.