i believe the roll out will be what you need to be the most accurate. to back this up, just take a tank "tread". in use, it has a super short "loaded radius". if you put it in a circle, it would be pretty tall. un-link it, and it is a set length, never changing length in any shape. i believe a tire acts the same. the tank tread will roll a set distance no matter the shape because of the "length" of the tread. it takes "x" time to cover "x" distance [roll out, or circumference] at "x" speed. we are not talking a top fuel slick growing at speed by any measure.