Just fyi, if you're careful with adjustment you can totally fit a 25mm tire in the back on an old p2c. I run a 25mm gp5000 right now, and I used to run a 25mm gp4000, which was even wider.

Not as fast as latex.

They are probably better than light butyl tubes, but still not as fast as latex. If you want fast, then latex.

https://www.aero-coach.co.uk/...e-rolling-resistance