What exactly does the rubber part of a ski boot do?

[millerm277]

The rubber heel. I was looking at it tonight while getting gear together, and trying to figure out what it does? I can't really see any purpose to it, since the boot gets locked in place on the plastic part, and the rubber doesn't seem to have any major function.

 

[wa-loaf]

The rubber heel. I was looking at it tonight while getting gear together, and trying to figure out what it does? I can't really see any purpose to it, since the boot gets locked in place on the plastic part, and the rubber doesn't seem to have any major function.

To keep the plastic from being worn down. Not all boots have it.