Truck driver's perception of ride quality/comfort is influenced by many factors relating to the driver, the vehicle and road surface roughness. A subjective rating survey was undertaken to identify the range of roughness wavelengths in the longitudinal road surface profile that affect the perceived ride of heavy articulated vehicles. They were found to range between 4.8 and 19.5 meters. Accordingly, a new roughness index called Profile Index (PI) was established. During the survey, data was collected on factors such as driver's age, years of driving experience, weight, vehicle's age, loading condition, cab location, type of driving axle suspension, weather condition and time of the rating. The effects of these factors were studied at different PI levels to test the viability of the PI as a measure of the perceived heavy vehicle ride and to establish if any of the above factors influenced the drivers' judgments during the survey. The effects of most of these factors proved to be not significant for the PI range used except for the cab location and time of rating factors. As the PI explains 83% of the variation in the mean panel ratings and the other factors account for a much smaller portion; it was concluded that the PI is a viable measure of the perceived truck ride.