Truck skid marks are routinely used as a basis for computing energy loss and the associated speed change. Cite specific coefficient of friction values, however, are most often related to passenger car tests. Therefore, to properly utilize truck skid data requires a correlation between truck and car responses to full braking.This paper reports the results of two series of tests correlating the response of trucks and cars under a range of similar conditions. The vehicles were instrumented in order to measure velocity and deceleration values during braking. In addition, length of skid measurements were made and related to vehicular response.