I have 10k on mine so far and probably 50% tread left. Usually, 555Rs see 12-15k. I baby my car and don't really abuse the tires that much, so they're lasting a good while. I expect to see 17-20k.
As far as rain or snow, they're useless.
I was stuck spinning my wheels in barely 3/4" of snow, and I learned to drive in snow up in Indiana. Then again, that's with 4.10s and drag radials...