Originally Posted by
cxwrench
There needs to be in every modern, non-UST set up.
No, that is not correct. IRC, for example, use a butyl lining to make their tires airtight. I’ve also run previous versions of Schwalbe One without sealant and Hutchinson Fusion 5 Galactik as well, presumably due to a butyl lining, but it may have been some other material making those airtight.
https://ircbike.com/pages/technology