Tire and wheel selection (rolling resistance / weight) impacts

So I’ve heard it mentioned a few times that x tire is worth y watts on the podcast bit without much context. The gear selection topics of race coverage has me realizing i should have been more proactive with my tires this year. The first was at a park called rocky gap, and lives up to the name as i pinch flatted a tire one year but the second race was very different. This place had some significant grass areas and the rest was buff st and gravel.

Looking back at the results of both races i was a minute behind my next age group placing. While I’m not sure gear selection would have made the difference in the first race, I’m thinking it really cost me in the second.

I’ve seen some tires advertise power difference at 20mph, but is this something as big as 20 watts with some really poorly rolling tires? Considering the grass surface…

So, I’ve got the decision to make… splurge on a race only carbon wheel set + xtr cassette or a bit more durable xc set + xtr cassette. I’m going to keep my current set for my home trails which are quite gnarly. The price point for the wheels are quite different for a 2-300 gram difference. But does rotational weight also affect power required to go a certain speed or is it more for accelerating to speed quicker?