Update for those who may have been put off by my comments about cornering on the sidewall:
I put a 26mm Specialized Turbo on my front wheel and that improved cornering a lot. It has a 31mm tread/66mm carcass. I was able to get close to the top 2% on a TOC descent (11k entries) - so definitely not slow, but not necessarily at the physical limit either. I could see myself shaving a few more seconds with this setup. And this is just with the front tire swapped to a 3 year old turbo. With front and rear Corsa Controls or similar I might be able to break 1%. In short, the wheels are not the issue. The tires are.
I suggested that tread and carcass width be measured at bicyclerollingresistance. To my surprise, Jarno obliged me and posted a ton of data for older tires as well.
As it turns out, the Pirelli P Zeros have the same tread:carcass ratio as the vittoria corsa speed tires - a TT tire that most agree has low grip. The Cinturato is closer to high grip tires like the Corsa.
The point is, you can definitely use a 25mm tire on these rims and maybe even some 23s. Just confirm that they don’t have a narrow tread and you’ll be good. Somewhere around 45% is probably ideal.
I know @
Ericoschmitt is using 23mm Corsa Speeds up front on these wheels. To that I say: you have bigger cojones than I do