Originally Posted by Racer Ex

Not all Ultremos are tubeless. My guess would be a bad match or bad tire. I've mounted a dozen or so Hutchinsons at this point with zero issues.

Beware trying to use a non tubeless tire without a tube. Tubed tires are not designed to work without a tube; while you can do the Stan's thing on an MTB with "tubed" tires and sealant, for road bikes it's not an option.

Both Schwalbe and Hutchinson make tubed versions of their tubeless tires (at least for the Fusions and Ultremos), you need to make sure yours say "tubeless". Why they take the risk and don't just rename their tubeless tire, I have no idea.