I am not sure it is safe to run 315s on stock wheels. Max recommended for stock wheels is 285 which is equal to 11.22 inches. 315 = 12.4 inches. Your wheels are 9 inches so get another set of rims. As far as height, dont try to shove them on. Get a beefier suspension setup.
EDIT: Its not the height to worry about, its the width.
+1 315 tires are to big to run on stock wheels, it can be dangerous.