Fastrax review and alignment questions for the pros.

The diameter of the rotational plane does not effect the toe angle because you are measuring the difference between the front and the rear. 0 is 0 no matter how far it is projected. It can be measured in degrees or inches, just go into the preferences and pick which one you want. Hell you can measure it in millimeters if you want. The computer is measuring it in degrees and converting it to inches of mm for us.
Degrees are measured from the center-line of the car and can be more accurate as it eliminated part of the inch measuring equation plus now we are measuring individual toe instead of total toe.