Originally Posted by
Duragrouch
Yeah... but... if I understand you correctly, just looking at the gear relationships doesn't account for difference in tire diameter/circumference.
Now Sheldon Brown's favorite, Gain Ratio, I think is more dimensionless, and even takes into account crank arm length.
Most people looking to select new gearing don't start by changing their tires, nor do most people changing their tires concern themselves with it impacting their gearing. Going from 25c to 32c tires is the equivalent of changing a single tooth on your large chainring.
So whether your top gear is a 122 gear inches or 121 is rather immaterial compared to figuring out if you have the range and steps that are useful. And any system can demonstrate that relationship.