Tires not holding air at high pressure
I recently built a wheelset for Tannus tire liners and studded tires. Then I noticed that both tires lose pressure quite quickly but one of these lost it in a very alarming manner (15% of gauge pressure loss per day).
For the tire that lost pressure not as quickly as the other, I estimate it was caused by the Tannus tire liner compressing due to the high pressure placed on it. Wait three weeks and the pressure loss has reduced to that of an ordinary tire. So it appears the Tannus liner is compressed about as much as it will compress.
For the tire that lost pressure quickly, the cause was mainly a loose Presta valve core. I didn't make it loose, it was that way straight out of the factory. I tightened it with an adjustable wrench and the quick pressure loss reduced to that of an ordinary tire.
So, moral of the story: if you buy an inner tube with a removable valve core, you can't expect the valve core to be fully tightened straight out of the factory.