The material that is being removed in the case at hand is cosmetic, not structural. It is the black rubber covering the white rubber that creates the white wall / raised white letters.
As an Engineer I know that a 3000# vehicle hitting or scrubbing into a curb is much more traumatic to the structural integrity of the tire sidewall than grinding a very small amount of the cosmetic black rubber that is covering the whitewall.
That being said I am not endorsing the grinding or machining method. It was merely posted as something that has been done for decades with successful results.
John
