Originally Posted by howardcano

As the front tires wear, the super-glued sidewall can form a thin lip, since it resists wear better than the normal rubber. Trimming the lip even or a little below the rest of the tire contact patch helps reduce the chance of tearing a section off when the lip starts flapping around, and reduces the possibility of the lip digging into the carpet (which makes the handling somewhat unpredictable).

You could also put the tires back on a truer, but lazy people like me don't want to take the time or effort.