Is there a way to put new rubber on Apple Earphones used with Nanos etc>

The rubber has gone away on the traditional Apple Earphones I use. It goes away in short time. The earphones themselves are still good, but uncomfortable now that the rubber is not there to cushion in my ear. Any replacement rubber rings, or do I have to buy new earphones? Any suggestions on an alternative to use to make them as comfortable as when the rubber rings are in place? The rummber rings also hold the earphones in place when I run and hike, and the phones are small enough and light enough that they do not add to the weight of the hiking gear or bother me when I run. In short, I like the Apple Earphones and would like to continue using them.
Thanks,