Automobile Tire Hydroplaning (1969)

[Music] everyone knows that cars skid on Ice you hit the brakes too hard and you slide you take a curve too fast and you lose [Music] control cars are more liable to Skid on wet pavement that dry everybody knows that too but what most drivers do not know is that with water on the pavement a car can behave just the same as on ice and it can happen to the car that you drive as well as to the test cars that you will see a misfill when you drive too fast you lose control you can't steer or break the car gets away from you and a skidding car is dangerous dangerous to you your passengers and other vehicles on the highway there are many factors that influence your ability to control a car on a wet surface the texture of the pavement the depth of the water the inflation of the tires whether they are smooth or have good deep Treads or a film of oil dust or dirt that is not washed off the pavement these factors in combination with the higher speeds of today can and do cause skids and accidents but of all of these factors you are the most important only you can recognize the danger signals and only you can do something about them modern research by industry and government has given us many insights into Tire Behavior at the NASA Langley Research Center in Hampton Virginia Studies have been made during the last several years on the behavior of aircraft tires when landing and taking off from water covered [Music] runways actual test films show what happens the wheels reach speed on dry pavement but when they hit the flooded surface they begin to slow down because the tires are actually lifted up off the pavement and are riding on top of the water this causes the wheels to spin down and they may even come to a complete [Music] stop further Studies have led the researchers to the conclusion that their work on airplane tires could be applied to automobile tires and that here is vital new information to tell the driving [Music] public Tire Behavior was studied by photographing the moving Tire through a glass plate installed in the [Music] runway slow motion films show the tire at a speed of 25 mph in 1/2 in of water here as we look at the footprint of the tire against the glass we can see that only part of the tire is in contact thus even at 25 mph a partial loss of traction has occurred by repeating the test at 50 mph we note the complete absence of contact between tire and glass the tire is actually riding on a layer of water and there is a complete loss of [Music] traction this is called hydroplaning very simply it means that the tire is riding on top of a film of water instead of on the pavement just like this attractive skier she is hydroplaning riding on top of the water here the upward Force which the water exerts on the ski is is dependent upon the speed of the ski at this speed the force is sufficient to keep the ski and the young lady on top of the water as the speed is reduced the then as the boat picks up speed she Rises to the top and is again hydroplaning of the water the same thing can happen to your car if you're driving too fast on wet Pavements the tires ride up on the water surface and hydroplane just as the skier did when this occurs you have no control over your [Music] car now when does Tire hydroplan occur when the speed of the vehicle tire pressure water depth pavement surface conditions of the tire whether smooth or good tread are so combined that the tire loses contact with the [Music] pavement research studies conducted by NASA have shown that new automobile tires will hydrop plane in less than 1/2 in of water and smooth tires in less than 1/10 of an in of water at the following speeds 42 mph when the tire pressure is 16 lb 51 mph and pressure 24 lb and 59 mph and pressure 32 lb but recall that partial loss of traction occurs well below these [Music] speeds further research studies have been made by the engineers of a Major Tire Company in England and here in their test lab you will see what happens to a tire under controlled conditions a large drum starts to roll with a load of 800 lb holding the tire against the drum then a stream of water is sprayed between the tire and the drum to simulate moderately wet highway [Music] conditions when the drum and tire speed is increased to 60 MPH we see that the tire is losing traction and spinning down the tire finally comes to rest and the technician can rotate it back and forth with his hand despite the 800 lb load a wedge of water is penetrated completely under the tire so that it is no longer in contact with the drum the National Aeronautics and Space Administration and the Bureau of public roads of the Department of Commerce conducted demonstrations to show what happens to vehicle breaking and steering when the pavement is wet a special area was prepared and tires just like you drive varying from smooth to good deep Treads were used in the test while it looks deeper the test surface water depth averaged less than 1/1 of an inch it was demonstrated repeatedly that on this moderately wet smooth surface cars equipped with tires having good deep Treads did stop in shorter distances Than Cars equipped with smooth tires at 20 mph good tires 40 ft smooth tires 65 ft at 30 mph good tires 100 ft smooth tires 165 ft at 40 mph Good Tires 185 ft smooth tires 300 ft a curve Lane test demonstrates that at 40 mph without applying the brakes the car equipped with good deep tread tires can hold the curve but at 45 mph the same car could not hold the curve thus loss of traction experienced on wet Pavements below hydroplaning speeds can result in serious braking and steering losses [Music] a change of Lane test at 35 mph on good deep Treads demonstrates that the driver has control but when the test is repeated on smooth tires the driver cannot make the lane change at this speed and Spins out of control thus under these moderately wet conditions the advantages of good deep Treads are obvious however if the water depth or speed were increased loss of traction would have occurred even with new tires as a further demonstration that automobile tires do lose traction and hydroplane in the range of normal driving speeds speedometers were connected to the front wheels of the test car and the tires on the right were driven in deeper water than those on the left upon entering the deeper water at 60 MPH the right front speedometer shows a spin down to 20 mph indicating that the right tire is hydroplaning that's the story and you play the most important part when Pavements are wet slow down loss of traction and hydroplaning can and does occur well below legal speed [Music] limits use good Ires be alert for wet spots especially when you can see standing [Music] water increase following distances adjust your speed to road conditions the highways are only as safe as you make them be a safe [Music] driver oh