im lowered with h&r ss springs and i run 275-40-17 all around and have no rubbing problems up front...im not sure about having 18s up front i doubt you will tho
i have 255/40/18 on my car and its lowered with h&rss and they rub the plastic on the drivers side if your cars lowered they wont fit. they 255/40/18 is taller than the 275/35/18 its got a good sidewall on it but it will rub only when you turn right.
Why would you want wide tires up front? Obviously your front wheels are your steering wheels and the wider the tires the more your handling is affected. I'd save the money on the tires and put it towards some huge beefy meats out back.