Max tire size - 68 dart

I have 255/40/18's on all 4 corners and I'm currently fighting rubbing issues on all 4 corners. I did plenty of measuring and it's tight. BFH has been my friend the past month. My fronts were rubbing on the studs of my GT trim on hard cornering. My rears, with a full tank of gas, tools in the trunk, and a passenger will rub against a ledge on the outboard side (quarter panels). I have about 1/4" or less between the tire and the springs. Stick with 245's for less of a headache. I am trying to make offset shackles work at the moment.