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.
Shaking Problems the FIRST thing you need to check is the tire pressure in every tire then check wheel balance It could be your alignment. If it's off it shakes. If the vibration is from about 45 mph and faster the tires are out of balance or bad.