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.
Part 1 of 3: Diagnosing tire and wheel balance issues. The most common cause of steering wheel vibration is due to tires and wheels that fall out of balance. Tire/wheel balance is the process of adding weight to the wheel after a new tire has been installed.