I am running 225/70/15 on the back of my '65 GTO, on repop rally one rims also. The car is stock height, and no clearance problems at all. As stated, it's all in the backspacing of the rims. I have run 12" slicks on this car without issue, too, but the rims had a ton of backspacing.
Whats the size of the Rally2?
I have a non-original rally2 rim in the trunk that has 7x15" with 4,25" BS. If that is the same size as original I think you can use up to 245's and the diameter can be as high as about 28". No real matter if lowered or not on the rear! (maybe it's an issue on the front..)
235's front and 245's rear....only issue i had was when springs were brand new the front lower tip of the wheel well would scrape front tires when i cut hard parking, since the springs settled in (lowered a bit) its gone away as the lip is not at the widest circumference of the tire now, but a bit lower.
My newly purchased 67 that Im trying to get road worthy came with 14 "fronts and 15" rear wheels . "MY" naked eye did not see this so I purchased 4 225 70 14's based on looking at the front tire only( lesson learned). Two of the 14's were mounted( thus cannot be returned). So I ordered the 225 70 15's then it dawned on me will they will fit.
I do not know if the wheels are 7" or 6" Is there a way to tell without removing the tires? I did think maybe that I go 14" all around but decided to purchase 15" tires