My tires are due for replacements. I have 18 inch OEM wheels (non forged Rays) on my 2004 G35 coupe. My question: What are the widest tires I can put on the front and rear wheels without any rubbing or sensor issues. I currently have 225 45 18 in the front and 245 40 18 in the rear. I like the ride quality and just want to make sure putting wider tires would not compromise handling. My second question: Has anyone used spacer on OEM wheels without having any issues? Any recommendations on make, type(with long studs etc) and the size in millimeters.I just want the wheels to look flushed with the body contours but nothing aggressive. The rear wheels are especially way to much inside the fender lines. Any comments will be appreciated.