70 dart wheels. Pro touring please help

Thanks for the reply, I will try and gather more info . It is mini tubbed in the rear. I am actually in the process of purchasing this car, it currently has 19x8 on the front and 20x 10 on the rear. not sure of any offsets or back spacing. was wanting to remove that wheel combo and step down to the 18 inch size. . I was looking at a certain wheel and those were the advertised offsets for them

Well if the current wheels fit the easiest thing to do would just be to find out the offset on those and go from there