<div class="htmlview paragraph">Methods of assessing the ride comfort afforded to tractor drivers by their vehicles and the ride improvement provided by seat suspension are reviewed in relation to information available on the human tolerance to whole-body vibration. Experience with different methods of measurement is reported and a proposal made for the establishment of an internationally agreed method of ride comfort rating based on standardized undulating surfaces over which vibration of the driver's seat is analyzed, using frequency weighting to represent the differing sensitivity of the body to different vibration frequencies.</div>