Sheldon say:
Hydroplaning
When an automobile is driven fast on wet roads, especially if it has worn-out tires, a cushion of water can build up under the tires, preventing the rubber from contacting the road. This is very scary and dangerous, because it leads to a total loss of traction. Fortunately for cyclists,
this cannot happen to a bicycle; they don't go fast enough, nor have a large enough contact patch, nor do the tires run at a low enough pressure to make hydroplaning possible.
Even with automobiles, actual hydroplaning is very rare. It is a much more real problem for aircraft landing on wet runways. The aviation industry has studied this problem very carefully, and has come up with a general guidline as to when hydroplaning is a risk. The formula used in the aviation industry is:
Speed (in knots) = 9 X the square root of the tire pressure (in psi.)
Here's a table calculated from this formula: Tire PressureSpeed
Miles per hourSpeed
Kilometers per hour P.S.I.Bars 1208.3113183 1006.9104167 805.593149 604.180129 402.866105 An ill-founded fear of hydroplaning often leads people to buy bicycle tires with inefficient
tread patterns, when they would be better off with
slicks.