The closest I have seen to an original source, and the numbers that seem to be quoted by most pilots:
Aquaplaning can occur when running in water and in cetain depths and densities of slush. Present indications are that simple dynamic aquaplaning is unlikely to occur in water depths much below 0.2 in. although under some conditions the minimum depth may be as low as 0.1 in. Once aquaplaning has commensed it can be sustained over areas where the water depth is less than that required to initiate aquplaning and to lower speeds that that required for initiation.
A simple formula has been derived from data obtained during trials which shows the relationship between the minimum speed at which aquaplaning may commence and the aircraft's tyre pressure. This states that the minimum initiating aquaplaning speed in knots is approximately nine times the square root of the tyre pressure in pounds per square inch. Speed in this context is of course in context of true ground speed and not indicated airspeed, although it not be precisely calculated...
HANDLING THE BIG JETS D.P. Davies
Page 188
(Typing errors are mine)
There was an old thread on this topic that had a link to a Dunlop site that was unteresting, but was lost in a server upgrade (sorry!)
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