A Tread-Deflection Measurement System Utilized in Tire Hydroplaning Studies

There have been several methods developed to measure film thickness, but most are not practical because they require physical disturbances of the material or flow by probe insertion. The tread-deflection measurement system was developed to investigate the transient response of a sliding tire as it encounters a change in free waterfilm thickness. The system is capable of measuring transient deflection changes in the contact region of a tire within one millisecond intervals. The system consists of seven capacitive sensors which are fixed to the inside surface of a tire and control the frequency output of integrated function generators which will accurately measure variable-induced displacements of less than 250 micro-inches. This system provides data in a form which enables evaluation of tire footprint shapes as a function of time for both steady state and transient hydroplaning conditions.