How to work out hydro planing speed?

[Wig Wag]

Given a tyre pressure in lbs how do you work out hydroplaning speed in knots?

Thanks.

[Manflex55]

If your question is about dynamic hydroplanning (aka aquaplanning), which occurs when standing water is not displaced fast enough to allow the tire to make pavement contact over its total footprint area, it occurs @ a min spd of 9 x sqrt[tyre p (PSI)].

Eg: for the 757 main wheels (inflated at 144 PSI if I remember correctly, which makes a convenient sqrt of 12), dynamic hydroplanning may begin at 108kt.

MF

[Wig Wag]

Thanks very much !

[HighSpeed]

wig wag,

for static hydroplaning speed, it is 7.7 x sqrt[tyre p (PSI)]. this happens when the tyres are NOT spinning, thus it is crucial to make a 'firm' touchdown to spin-up the tyres when landing on a wet runway.

HS