Will these 18's fit?

[Steve C]

Hi

To get an idea of how things may look I use a known wheel size that fits in http://www.1010tires.com/WheelOffsetCalculator.asp

In my case I know a 7x16 wheel with a 23 ET (Fuchs) fits under stock fenders.

So comparing your new rear wheels you would have 80 mm less inner clearance and 4 mm more outer clearance under stock fenders. So your going to need some pretty wide spacers to fill your rear fenders.

I'm not sure about your fronts because that depends on your car model.

Steve