A series of acoustic and vibration measurements were conducted on four heavy truck tires, utilizing a roadwheel facility enclosed in a semianechoic chamber. Data were recorded from five near-field microphones and from five accelerometers mounted inside the tires. Acoustic time signatures were analyzed to identify source locations and possible generation mechanisms. Excellent agreement was obtained between air pumping theory and measurements for a crossbar tire. Tentative agreement between air pumping theory and measurements has also been obtained for one rib tire.