roll out is just the amount of distance your wheels will travel in a single turn of the motor.
what kind of car do you have? to calculate roll out you have to know the pinion size, spur gear size, final drive ratio and the diameter of the tires.
if you can post what kind of car you have we can walk you through the rest and point you to some charts or give you an excel file to calculate it, there have been many posted on this site over the years for various cars