Sorry, but I lost you at "and measure out the front side around 15 inches from the spindle center and then about the same amount out the other way and see how much difference there is"
The 15" measurement "out the front of the spindle and the same amount out the other way" would be about the same as measuring at the front of the tire and measuring at the rear of the tire. He is just taking any variable the tires may cause out of the picture.
Definitely more accurate, but also more difficult because you need to jack it up, remove the tires and set it on jackstands under the control arms so the weight is on the suspension, then use a straight edge placed against the rotors to measure across. Gene
