This paper shows some discussions regarding an experimental consideration of booming noise level when a vehicle drives over a small protruding object on a road. Booming noise level is subjected to vehicle speed and is not proportional to the speed. Generally, it is known as the maximal noise level is being created with vehicle speed of around 40 km/h, however, the obvious cause of the phenomena have not been completely determined so far. In this paper, at first, it shows an experimental data that was being observed in detail with variable vehicle speed. Based on our detailed observation of the experimental data, reversed-phase two inputs by existence of a protruding object, was confirmed. By considering correlation between time difference of two inputs and vehicle speed, it is demonstrated that those two inputs around 40km/h induce a tire resonance which leads to a booming noise in a cabin. We define it as ‘harsh booming noise’ here.