Originally Posted by friction
In my direct experience on my own cars, it only makes a huge difference in steering feel and tracking if you change the offset drastically. like changing your offset by 2 inches to get that hellaflush look.
Most folks would not even notice a difference if the offset changed 10-15mm. I havent done the math but im guessing the track width alone on all the new 2012 focus tire options varies by at least that much or more.
a little lower offset if you are upgrading wheels is not a big deal. You get a wider track width. If you are having tracking issues, check your alignment, it may be within spec but that hardly means its accurate or straight.
I agree that up to 15mm change in ET is probably not a problem.