1. (Units) a unit of heat in the fps system equal to the quantity of heat required to raise the temperature of 1 pound of water by 1Â°F. 1 British thermal unit is equivalent to 1055.06 joules or 251.997 calories.
Quick Answer. A major factor that usually causes tire noise is the air chamber inside the tire. The large void that is filled with air acts as a giant resonance chamber. Thus, the tires are something like donut-shaped drums that generate a low-frequency hum when tires are rolling.
1 Tire Damage â We often over look our tires and we seldom check for problems or damage. 2  When tires are worn out we sometimes see BALD PATCHES, EXPOSED WIRES or BULGE PATCH, these cause vibration when reaching a certain speed.