I still haven’t found anything compelling that tells me my choice for 40s at my last race wasn’t the right choice, for that course. I’m still very interested in finding some factual information that might change my mind.

“Wider is faster” isn’t universally true. There’s an understanding that a wider tire is faster than a narrow tire, at the same pressure. However, if you’re running wider tires, you’re also probably running them softer. BRR data shows us that the 40 Thundero is lower cRR than the 48. BRR also shows us that the same tire with more pressure has lower cRR. Silca’s testing showed the same thing…up to the point that it isn’t. Determining that breaking point is the magic trick, isn’t it? How do we (performance-interested amateur racer) determine that? There’s also the factor that the entire course isn’t the same texture. So, how do we make the judgement about the best overall choice? Until I have a better way, I’ll use my best judgment on width based on my experience/preference, use the Silca pressure calculator, and run (probably) a little less than that. Got a better way?