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.
If your rear-wheel-drive car or truck is making a howling sound that seems to be coming from out back, this can be a symptom of a problem with the differential. A variety of noises can be produced by one of these components in different driving situations, from acceleration to deceleration to steady-state motoring.