Everyone here is going on long rides and compares, adjusts, repeats. Wouldn't it be easier, quicker, and maybe more accurate to just do a roll out in front of the house.

To take some of the fuzziness out of your measurements out of the equation, roll it out about 8-10 full revolutions and then take a measurement. Take that number and divide by the full number of revs. I shouldn't be off by more than a few mm's that way.