A tyre's exterior noise grading is expressed in decibels (dB).   To help you make an informed decision, PitstopArabia.com makes the exterior noise rating of every tyre, where possible, available to you.  Choosing a tyre with a good noise rating will minimize the impact of your driving on the surrounding environment.  Increase of noise of just a few decibels makes a significant impact.  The quietest tyres have a decibel rating of 68 or below.   The loudest tyres would have noise levels of 72dB and above.These grades are neither applicable nor available for professional off-road tyres, temporary-use spare tyres, studded tyres, tyres used only for racing, tyres whose speed rating is less than 80 km/h and tyres whose nominal diameter is smaller than 254 mm or bigger than 635 mm.