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.
Excessive vibration while traveling a constant speed, especially highway speeds. 1  Wheels out of balance - have wheels re-balanced. 2  Tires worn unevenly or excessively. 3  Loose wheel bolts - check wheel lugs for correct tightness.  Warped brake rotor - inspect brake discs (rotors) and replace if needed.