Parameters Affecting the Noise Performance of ASTM Standard Reference Test Tires 2013-01-1910
Currently, the ASTM P225/60R 97S Radial Standard Reference Test Tire (SRTT) is used as a control test tire for calibrating test track surfaces over time and for rank ordering the noise performance of different pavement designs. As a result, variation from one SRTT to another and the effects of tire aging are important to quantify. Measurements of tire noise sound intensity on eight asphalt and two concrete test sections were conducted for eleven new and six older SRTT tires. The range in level for the new tires on each of the ten pavements was determined and was found to be 1.1 dB when averaged over all pavements compared to 0.7 dB for a single tire tested multiple times. As a group, the older tires produced levels 0.5 dB higher than the new tires when averaged for all pavements. The older tires had higher tread rubber durometer hardness values than the new tires, however, within the old and new groupings, no consistent trends could be identified. After nine months, the original 11 new tires were retested with some tires being subjected to mileage accumulation, accelerated aging, and wheel width changes. It was found that the effect of tire aging variables including hardness, tread depth, time since construction, and mileage, were not necessarily consistent from tire-to-tire. However, considering the extremes of durometer hardness, reduced tread depth, accumulated mileage, and in-service years, a strategy for deciding when test tires should be retired was developed based on a combination of these factors. Due to the varying temperatures at which the measurements were made, an adjustment of tire noise level for temperature was developed as part of this research.