Originally Posted by jonbth
Mountain bike tubeless tires and wheels are similar to automotive tires and wheels. The rims are clinchers and the tires have a special bead that fit tighter than standard tires and the rims are sealed to allow you to run tires without tubes.
I hope this explains it a little better.
Thanks for the heads-up; I must have missed the fact that it was posted in the MTB forum; oh well, it's not the first time, and certainly won't be the last!
- Wil