I wouldn't use a tube with a new tubeless tire on an alloy wheel. If I had a puncture in the tire I would probably tube it rather than patch it. Patches and plugs are long term solutions for some folks, but I only trust them as roadside emergency repairs. As stated by farm, I know some people who have sealed up spoked wheels to run tubeless. Never made much sense to me. Adds more rotating mass than a tube, harder to balance than a tube, much more prone to leaks than a tube. That being said, I run alloy wheels, no tubes, and beads for active balancing. As a side note, I really enjoy the cleaner look of a wheel with no weights on it.