The objective of this paper is to compare the site-to-site variability of ISO 10844 pass by the noise test sites. In order to investigate the site-to-site variance of test surfaces, European commercial tires are tested at seven different test sites. Three Korea test sites and four Europe test sites are selected. The pass by noise test is done according to a 2001/43/EC regulation. Although the ISO surface has a very specific track composition, it does not reduce the variation of pass by noise measurements over the surface of test sites. This paper shows that the test results of pass by noise level are different depending on the test sites. The correlation obtained in this work is able to predict the pass by noise level for certain test site using the data measured from another test site. The prediction value is range with an error within 1 dB(A).

Among many potential problems associated with passenger cars, the problem regarded as most sensitive and important to the customers is the passenger car’s quietness. In particular, because the trend toward the high-performance passenger cars is increasing, the quietness should be considered reflecting the increasing demand of the customers for the comfort of passenger car ride. Road noises are of low-frequency in the region of 20Hz to 350Hz, generated when the tires are making contacts with the rough road surface while the passenger car is running, in which the noises are resonating within the passenger compartment or with the passenger car suspension. In this research, among the factors related to the road noises, the influencing factors associated with the suspension and the tire design were investigated. In particular, among the tire design factors, the structure and the rubber material were investigated as the influencing factors, and for the investigative purpose, experimental tires were manufactured and road noise evaluations were conducted thorough actual feeling tests. Then the test results and correlations were analyzed using the 6-Sigma statistical method.