I have 5 powerchairs. 2 in my room, and 3 in the kitchen. Once a month its a pain in the ass to check all tyre pressures.
Even with tubeless, in the rears, and tyre puncture sealer in all 20 tyres, there are always at least half that have dropped pressure very significantly. The odd one is really low too.
So as an experiment I replaced all 20 valve cores. A month later and a small improvement generally. So it made me think...
I ordered 20 alloy valve caps. With a rubber sealing ring. And re did all pressures and fitted them. And 1 month later most of the tyres had lost literally nothing I could measure. With the odd exception. So a huge improvement.
They are black annodised with sealing ring from amazon. With a smear of silicone grease on the threads.