The Cobra replica rims made for the fox body mustangs are usually 17x8. The backspacing on a mustang is right about 5 inches. So with an 8 inch wide wheel to find offset you take 5 inches of backspace - the centerline of the wheel, which is 4. So you would have an offset of 1 inch. 1 inch = 25.4 mm. So in other words you would have a wheel with a +25.4 mm offset. A focus needs a wheel with at least +40 mm offset. So what I am getting at is they will fit, but they will look goofy as hell.
the offset of some of the rims i found were only 20 and 26. so i believe that is quite a bit off compared to the focus. that is a 17x8.5 mustang rim. i din't know what that means really but that offset is way off. i did find some however that would look amazing on a focus if only that offset was better. 17x 8.5 or 17x9 would look sick on a focus. wish that offset was better cause it's a great idea and easy to find affordable rims that way.
He may be looking for the Cobra R version which I allso looked into puting on the focus but gave up after seeing the problems I would have with the offset. If you like 16" rims the Cobra R style was on the SVT Contour so you might be able to find a set of those.
Thanks for all the help guys Yeah, Stang I was looking at the Cobra R version and I found a couple sets on Ebay for about 600 bucks , but turns out that im not going to be getting the money I thought I was so ill be waiting a little while anyway. But thanks for the info guys It was a big help and will be when I do get the money again to buy some.