You will not have any issue. The difference in aspect ratio (% of Tire width) from a 40 series to a 45 series amounts to less than half an inch in sidewall height - 0.452" to be precise.
It may have a different feel in real high G maneuvering (not necessarily bad, just different) but I doubt you'd notice it on the street.
To keep the same sidewall height (approx), you'd have to drop to a 195 tread width and that would adversely affect the car's handling and feel.
