LOL at lowering the DD and not the Z. But I agree better not to mess up a good thing especially when the Z looks good how it stands now. Just keep doing what you are doing with your cars. Even with scraping, atleast we know both your cars will be as clean as a babys bottom.
Anyways, didn't mean to deviate the thread, but yeah Big you shouldn't have a problem with 18s heres an idea of how 18s would look on an altima. That wheel gap is a killer though, if this person lowered it, it would be perfect.