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.
Unbalanced tires can create a small hum, a slight shake or a significant vibration that makes driving the vehicle unpleasant. Steering wheel and seat vibration is a frequent sign of unbalanced tires. This type of vibration is distinct and gives information about which tire is unbalanced. When the front tires are unbalanced, the vibration is experienced in the driver's hands through the steering wheel. When the rear tires are unbalanced, passengers feel shaking in the seats. Excessive wear on the tires occurs when the tires are unbalanced. Unbalanced tires cause increased stress on a specific area of the tire. These stresses combine with the uneven motion to cause vibration, which leads to excessive wear and a greater risk of deflation.