Two sizes of wheels and tires were available for 67.
Base size was 14x5 wheel with 7.35x14 tires which equals about a 185-85-14
Your SS would have had the optional 14x6 wheels with D70x14 tires. I'm not sure of the metric on that one, you'd have to calculate it by figuring the height of the tire/wheel combo, subtracting the (14") wheel diameter, dividing by two, multiplying by 25.4 (to convert to millimeters) and taking 70% of the result. The use that number to fill in ???-70-14