Thanks for the link.
For those unfamiliar with the decibel scale, it is logarithmic, so 6 dB = twice the sound power, 3 dB sounds to the human ear as twice as loud, and 1 dB is barely noticeable.
According to this article (and that is my understanding) 10 dB is aprox twice as loud to the human ear.
Either way, I think what most tests and people are missing here is the point of view. Inside the cabin there is little difference. To a pedestrian the difference could be much more noticeable. The tires are exposed sideways while the wheel well is padded and insulated. We hear the tires very little inside the car. Even when we roll down the windows. But drive by a wall where the sound from the tires bounces back and you suddenly hear the tire noise very good.
In other words, there might be a significant difference in sound to people outside the car with foam padded tires, while there is little difference inside the car.