I'm not sure why I first tried 25s. Might have been a friend's suggestion, a fluke buying the "wrong" tires or curiosity after reading about them.
Turns out few high-end production road bikes have frame and fork clearance sufficient to accommodate 25mm tires. Virtually all road bikes come equipped "standard" with 23mm tires, the industry default.
Because it's what the bike comes with, most riders just get the same thing when a tire wears out. No questions asked.
I'm not even sure if my old Time fork equipped Lemond could accommodate 25s. I never checked. Just kept buying 23s.
I'm glad my flamescaped Landshark with Reynolds Ouzo Pro fork could though. I had these two tires and would have been frustrated to have to exchange them. Nice blue tread too.
On went the 25s, and after one ride I was hooked.
I wasn't looking for or expecting some remarkable new riding experience. But there it was. Riding along an average road with an average surface was noticieably smoother and faster.
When the going got rough is when I really noticed the ease at which I could maintain forward motion. The little bumps were smaller. The bigger ones not so big. I noticed I was cornering more confidently. Just that little extra bit of stability helps on a zippy descent.
The slightly larger profile also evoked memories of Clement's delightfully round Campione del Mondo tubulars we rode back in the day.
I didn't need to read all the data suggesting, gram for gram, pressure for pressure, 25s offered lower rolling resistance than 23s. I didn't need to comb through physics force theories or the science of tire casing deflection.
I do like physics though and simply put the larger diameter casing of 25mm compared to 23mm reduces the size of the force vectors applied to the tire in a direction that would resist forward motion. Yes, even that small amount makes a noticeable difference.
Recently, Tim Neenan of Lighthouse Cycles built a Columbus Spirit frame for me. It was difficult to find a stylin' fork that would accommodate 25s since Reynolds ceased production of their brilliant Ouzo Pro. (What did actually happen that caused Reynolds to stop? A lawsuit perhaps?) But 25s are now a requirement and I chose a True Temper Alpha Q GS 10 (also now discontinued).
I believe 25s offer such an advantage I now consider them my secret weapon.
So, I'm happy those shiny new road bikes on the shop floor only fit 23s. I'm glad when you're buying replacement tires you'll be reaching for 23s. I'm pleased as punch you won't be checking to see if 25s fit on your bike.
Hey, 25s and a stealth triple (don't look too closely) are about all I have, empirically speaking.