Tire-pavement interaction noise (TPIN) is a dominant noise source for passenger cars and trucks above 25 mph (40 km/h) and above 43 mph (70 km/h), respectively. TPIN is generated due to excitations of the tread pattern and pavement texture. For the same tread pattern and pavement texture at the same speed, TPIN might also be influenced by the tire structure (e.g., the tread rubber hardness and tire size). In the present study, 42 tires with different rubber hardnesses and/or tire sizes were tested at five different speeds (45–65 mph, i.e., 72–105 km/h) on a nonporous asphalt pavement (a section of U.S. Route 460, both eastbound and westbound). An on-board sound intensity system was instrumented on the test vehicle to collect the tire noise data at both the leading edge and the trailing edge of the contact patch. An optical sensor recording the once-per-revolution signal was also installed to monitor the vehicle speed and, more importantly, to provide the data needed to perform the order-tracking analysis to break down the tire noise into two components. These two components are the tread pattern noise and the non–tread pattern noise. It is concluded that for the nonporous asphalt pavement tested, the non–tread pattern noise increases with rubber hardness by ∼0.23 dBA/Shore A. The tire carcass width (section width plus two times section height) influences the central frequencies of the non–tread pattern noise spectrum; the central frequencies decrease as the tire carcass width increases.