Interpretation ID: nht69-1.4

DATE: 09/02/69

FROM: C. A. Baker; NHTSA

TO: Garis, Trezza, Ithurburn and Keely

TITLE: FMVSS INTERPRETATION

TEXT: Your letter of August 6, 1969, to the National Commission on Products Liability has been referred to the National Highway Safety Bureau for reply.

Vehicle skidding is a function of many parameters within the tire-pavement interface. The most adverse tire-pavement interactions occur when pavement is covered with water. Under certain wet pavement conditions, complete loss of traction or hydroplaning occurs. The two possible hydroplaning phenomena which may occur are viscous hydroplaning or dynamic hydroplaning. Both of these conditions of hydroplaning to a degree may be controlled by the proper selection of pavement texture and tread-depth of tires.

The detection of hydroplaning as the causation of accidents is most difficult to establish and although we have many accident studies in progress, I would seriously doubt that hydroplaning can be successfully isolated from the common form of skidding.

The tire manufacturers recognize hydroplaning and they do provide adequate water escape passages as well as tread depth to copy with this problem. However, the tire is only a subsystem within the tire-pavement system of hydroplaning.

For further information on this subject, I suggest that you contact the National Aeronautics and Space Administration who's research history on hydroplaning dates to 1958.