I have a Metzeler back tire with such a small puncture (right in the center) that it will only deflate down to about 15lbs. In other words, it won't go entirely flat. When aired up to 40 it leaks out in about 20 min.

So I'm thinking of plugging it with a simple plug kit; anyone else have experience with this? The tire is still very much a good tire. I hate to buy a new one over a simple flat.