In order to evaluate and improve the level of tire road component noise, test methods for the tire road component noise separated from the whole vehicle noise have been studied. The trailer method is one of the best methods in a sense of eliminating the vehicle influence. However, the accuracy of the trailer method greatly depends on the technique of tow vehicle noise correction.
The most basic and complete correction technique is the time history correction method that is mainly used in the academic research field because of its accuracy. However, the time history correction method requires a rather complicated signal subtraction process in time domain. Therefore it is difficult to use in daily practical testing for tire development.
Instead of the time history correction method, the long drawbar method and the drawbar length correction method were studied by simulation case studies and experimental works. In these case studies the carpet surface and the sound barrier technique were introduced in order to realize the very quiet tow vehicle conditions and it was verified that the quieter tow vehicle brings better results.
No tow vehicle correction is required provided that the tow vehicle is quiet enough. If the tow vehicle is not quiet enough or if the test tires are very quiet, the time history correction method is the safe and steady method. The drawbar length correction method, however, can be applied as the substitute of the time history correction method in many cases.
