Originally Posted by Sy Reene

I guess it's just my theory, but can't say I've seen anything contradictory yet, but Silca spits out what they deem 'optimal' (for lack of a better term). Ie. what yields fastest speed for the given parameters for a given power input. That is, what data is out there that, providing an average weight rider would be within safe operating levels regardless, that a tubeless tire should be run at a lower PSI than a tubed tire to yield max speed for provided power?

We know that a tubed tire setup can be run a max pressure higher than Tubeless hooked, which in turn can be maxed at higher value than hookless Tubeless. On the flip side, the tubed setups can't be run at as low of pressures as the TL options without more severe risks of pinch flatting. Perhaps the returned values for Zipp's calculator is to match the marketing if they want to rate a rim as ok for certain max rider weight and the likely tire width that rim is optimized for? On the flip side, Silca seems to disregard any tire, rim or weight ratings, and effectively is telling consumers to figure that part out for themselves.