What size tire/rim is the widest, lowest profile that can fit G35 without modification?

I have a 2004 Infiniti G35 that comes stock with 245/45/18's all around. I was thinking of getting 20 X 10 inch rims and putting 255/35/20 in front and 295/30/20 in back. I'm thinking the off sets will be different front to back, but will it fit without rubbing anything?