A British thermal unit (Btu) is a standard unit of energy that is used in the United States and sometimes in the U.K.
There is another defect in tires that can cause a vibration called loaded road force variance. The tires and pass a visual inspection, a radial and lateral runout test, be perfectly balanced, but still cause a vibration. This is due to the internal defects in the tire.
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.