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.
Check your wheel balance. Have a tire shop check and rebalance your wheels. An off balance wheel can cause lots of vibration. This is a cheap fix if it's your problem. Replace your shock absorbers or struts. Worn struts or shocks can cause an uneven driving condition and can result in shaking, porpoising or bouncy ride.