Appreciate the response. To be honest not really sure what offset means haha. But I guess thats my main question, would any 245 45 18’s work? I would think so because theyre all the same size but I just wanted to make sure before buying anything
Hi deannj. As DaMiFo stated, not all 18" wheels will work. Unless you are buying from a seller who guarantees the fit (such as The Tire Rack etc.), you really should learn what "offset", "bolt pattern", "centerbore" and other wheel terms mean. Or at least have a better understanding, before you buy something you may not be able to return for a refund.
Just as an example, and perhaps I am mistaken, but you sometimes seem to refer to "245 45 18’s" as though that is a wheel size. However, 245/45-18 refers to a tire size that fits on an 18" wheel. So yes, a 245/45-18 will fit on a Fusion, on a properly sized and spec'd 18" wheel. However, you also must make sure you buy a set of 18" wheels that fit the Fusion (i.e. the proper offset, centerbore, bolt pattern etc.).
So also going back to your original post: Yes, any 235/45-18 (or 245/45-18 etc.) tire will fit the Fusion, as long as it is on a properly sized and spec'd 18" wheel. So that means an 18" wheel with the correct wheel width, offset, centerbore, bolt pattern etc.
Take a look at this link and read the explanations/definitions of those terms mentioned above (and others). Then you can make a more educated decision:
https://www.tirerack.com/tires/tiretech/tiretech.jsp?tab=Wheels
Let us know how you make out and good luck.