ya gap doesnt look good.
i would like to know the offset of the wheels to make the best answer. the width is important too. if you get a tire too wide your handling will go down if its on a skinny wheel. and if you get a narrow tire on a wide rim is gives it a stretched look. which i dont like on a street car. track only car yes. improves handling but at a cost.
i like the tire to line up with the rim. so if you have a 8" wide rim i would go 235. thats the best looking size on that rim imo.
but for me 235/45/17 is better than 225. but it depends on wheel width. the 235 will be taller and wider. it might fill the gap better than the 225. but if you lower it you might want 225.
i can help you but you need to tell me the width and offset