I guess I'll be of some use to this forum....
Here's a tire that has been chalked:
If your tire is over inflated, not all of the tread will be making contact with the ground and therefore not all polish on the tread will wear off.
If your tire is underinflated, the tire will rollover onto the sidewall and wear off the polish there. This is obviously bad, because sidewalls were not made to grip.
If your tire is inflated correctly, only the tread will contact the ground during your runs. The chalk or shoe polish will wear away on the tread, and not the sidewall.
