Boosted150crew

Hey guys I just my 5100's on last night and I love them. I did the setting second from the top and the truck is level. Anyway now I am looking for wheels and tires. I think I am gonna go with18" Method Racing Wheels. I also think I am going with the Falken Wild Peak tires. My question is should I go with the 285/65/18 the 305/65/18 or the 325/60/18? My truck is a 2wd. I want to keep as much gas mileage as possible but I don't want the tire to look small in the wheel well. Thanks for the help