The ability to view the tire footprint and simultaneously to measure the tire-to-road surface interface forces is essential to the investigation of parameters affecting high-speed passenger tire performance on wet surfaces. The tire is photographed from below through a glass plate; the tire-to-road surface inter-face forces are recorded for various combinations of tire types, inflations, loads, wear conditions, water depth, and vehicle velocity as the tire passes over a triaxial force pin.The facility and test method are described for the evaluation of pneumatic tires at all modes of operation: free rolling, sliding, and free rolling with a slip angle. An empirical equation is given to estimate the hydroplaning speed of a passenger tire on a smooth surface in a single mode (free-rolling) of operation. The parameters that affect tire hydroplaning are discussed as are some of the conditions that may influence the method of test. Implication is made that these factors and parameters also are related to high-speed wet surface braking distance.