Shadowman, those might not be bad if you could get them into the Schreader holes as designed instead of just using them as washers. But the size difference between the Schreader and Presta is much less than what such grommets are sized for. I know because I built and serviced electronics equipment for years that used such grommets. For example you'd need a 3/8 hole to mount a grommet of that type which would have a 1/4 inch hole to accept the Presta stem.

So some washers just for padding and to spread out the pressure is all the "grommet" that will fit or that is needed.