Originally Posted by
jonwvara
I believe that the clearance between brake and tire will increase as the pads wear.
My experience - the main part of pad wears and forms a "lip" that reaches over the radiused upper edge of the rim and works its way towards the tire.
My suggestion of chamfering is to remove that material before the lip forms.
Lowering the brake pad moves the upper edge onto the flat sides of the rim, below the radius.
Both options are meant to stop wear from allowing the pad to contact the tire.
It's up to you.