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.
Low-profile tires, a 40-series tire compared to a 65-series tire, typically generate more noise because there is less rubber sidewall to absorb it. This noise gets transmitted through the chassis and the rest of the vehicle. Tipping the balance to traction, many are put off by excessive tire noise. Wide tires, a 265/ tire compared to a 235/ tire, generate more noise than narrow tires because there is more rubber in contact with the road. More rubber is more traction, but also more noise, again showing the effect of tipping the balance. Each tire type also has a unique sound profile.