front backspacing

What width rim are the 245's on? What's the backspace?

If they're factory rallye's they're probably a 6" wide rim at most? Meaning, the 245's are really squeezed on there, that rim is a full inch narrower than recommended for that tire. That significantly changes what the tire profile looks like.

That also changes the location of the outer edge of the tire. Remember, if two rims of different widths have the same backspace, they don't have the outer edge of the rim in the same place, the centerline of the rim has moved. The easiest way to look at that is the rims offset. A 15x7 with a 3.75 backspace is a -6mm offset. A 15x6 with a 3.75" backspace is a +6 offset (like most of the factory rims were, BTW). That difference means that the outside edge of the rim moves by a 1/2" between those options, even though the backspace is the same. Offset keeps track of the centerline of the rim even when the width changes, backspace does not.

With a 15x6 that has 3.75" of backspace a 225/60/15 should fit the car fine, and the 15x6 is still in the recommended range for the 225/60/15's.