This type of noise occurs often in vehicle with block-or lug-pattern tires when driving on paved roads. It increases in volume with the vehicle speed.
1.Main cause
Air-pumping effects of the tread pattern.
2.Mechanics of noise development
(1)When a tire turns on the road surface, air gets trapped between the tread grooves, and the air is compressed upon contact with the road surface.
(2)As the tire keeps spinning, the compressed air is then freed from the tread – this is called “air-pumping action” – and expands when released, creating a popping sound. The multiplication of these sounds produces a roaring noise.
Tires with patterns which easily trap air have a tendency to produce louder roars. In other words, the block or lug tread pattern is more likely to generate noise than rib pattern.