On my 69, I have 225-70-15 Goodyears on Torque Thrusts with 4 1/2" back spacing. I have tire rub on one of the bolts in the wheel well, and I haven't installed the wheel well moulding yet.

I don't want the expense of changing wheels, and I want to stay with 70 series. What is the largest size that will fit.

Part of the problem may be in the 70 series tires. The 225/70 tire is almost 27.5 inches tall- this is why it is rubbing. I think the maximum recommended height for a front tire on a '69 is about 27 inches. If you use a 225/60 tire it will only be about 25.5 inches tall, and a 225/65 series tire is 26.5 inches tall.

You could approach this two ways- use a shorter sidewall tire (60 or 65 series) or install a spacer between the springs and frame to raise the car 1/2 to 1 inch for use with the 70 series tires.