Is this a 18x8 wheel? Measuring from the inside of the wheel lip I get about 8” but from the outside of the wheel lip we’re at 9”.

 

Correct inside the rim to inside the rim. Dimensions usually marked on backside of rim, inc backspacing or offset

 

Door jam should tell you.

 

I think Stock ford 18s are 7.5 in wide rims... my sport 18s are for sure...

 

The Al. / PVD 18's are 7.5" wide, the rest of the 18's are 8.5" wide:

 

Wheel width is measured from inside to inside of the rim, ie. where the tyre sits, you can end up with half to one full inch extra when measuring outside to outside on the rim. But yes, most stock Ford wheels are 7.5" wide and will normally be on the back of one of the spokes.