Perhaps worded wrong,....2 lbs a week is perfectly normal for any type of tire that has a slow leak

Is that better?
I have about a 1lb per week leek in my ATV (tubless) trailer tire, and I can't find it. I've had the entire thing covered w/ soap, and nothing ! So using case law, 1 lb per week is normal,.....for that tire anyway.
I also was in a tire shop for a couple years before tubeless, and I can remember tube type car tires (tubes) having slow leaks that could not be found,.....leaked under pressure only, so we just replaced the tube.