Largest 14" Tire Size For 69 Swinger

I have 205/70R14 on my stock 67 dart with stock steel wheels etc, saggy springs. plenty of clearance front and back, BUT... there is signs that the rear tires have rubbed the inner fender well a little. Its not from straight up and down (there is 1 inch inside and outside tire to fender clearance.) it is a convertible so could have something to do with body flex?