275/40-18 is 26.7"; that is a bit tall for the front! I have 255/40-18 on the car now (26") and ultimately plan on running 275/35-18 (25.6"). Did you do the front fender mod? If not you will not be able to go that tall... tire will hit fender when you turn. I think you did, I just wasn't sure. Not aware of a 325/30-18; 335/30-18 yes. I like the 325/30-19 myself.