[stephen145c]

If i put 18" rims on my mustang will i need to lower it to fill the gap between the wheel and fender? Or will the bigger wheel fill the gap?

[ajaxthemax]

I went from 17's to 18's myself and I lowered the wall height of the tires that I put on the 18's by 10......they fill the well nicely.....If I had left the wall height the same as the stock tires, then it would probably rub (when going over bumps only).......I'm not sure what kinda look you want though........?????

[Stoenr]

It all depends on the size tire you run with. Compare the 2 tires overall diameter, that will tell you.

[GuitarstarX7]

I went with 245/45/18 and it doesn't rub.