Ewww those are long and tangled docouments. I suspect I too will be busy for some time. A first read gives a new value (new to me at least) for hydroplaning speed on p22 of the CS25 amendment as far as wheel/ground friction is concerned. "For the purposes of estimating the effect of aquaplaning on contaminant drag, the aquaplaning speed, VP, is given by - 𝑉𝑃 = 9√𝑃 where VP is the ground speed in knots and P is the tyre pressure in lb/in2 . To estimate the effect of aquaplaning on wheel-to-ground friction, the aquaplaning speed (VP) that is provided above should be factored by a coefficient of 0.85." I also notice that Appendix 5 of the ICAO doc (page 55) assumes a 1.67/60% factor on dry runways for turboprops.