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.
Tires. A variety of tire problems can cause a vehicle to vibrate. Tires with unevenly worn tread are one of the most common culprits of a vibration. The vibration is caused by the varying levels of tread coming in contact with the road at the same time, creating an uneven ride.