Acceptable tire pressure loss?

You should be checking tires every trip. If they are lower than required then add air to bring them back to where you want them. The pressure will drop as the ambient temperature lowers. Also; tires with lower pressure can loose air through the bead when cornering.

I prefer to keep my tires within 5% of sidewall maximum. Harder tires tend to hold air better.

There is no normal for tires because of the multiple reasons for loosing air; small tire puncture (nails, etc.), sticking air valve, leaking bead, etc. The vary reason the manual and maybe a warning sheet inside the RV recommends check tire pressure, inspect tires, and lug bolts each trip.

Thanks for the responses. When I dropped it off to storage it was 104* outside. Yesterday when I brought it home and checked pressure in the evening it was about 83*.

While 3 pounds over a month may not be that unusual, neither is it that usual…
While not losing sleep over it, it is enough I would pay close attention to them and try to find out if there is a cause first, like leaking valves or tire seal which are not acceptable IMHO…
my tires so far may lose on average 1 pound over 3 months even with all the variables mentioned…

the quality and amount of inner liner material for the most part will determine what is normal air loss…

Acceptable.

After two months in the cool Alpine region of New Mexico all 4 of my brand new tires on the fifth wheel dropped 10#s. From 95 to 85 p.s. i. The truck tires didn't lose any air.

Other trailer owners had similar loss. Is it the way trailer tires are made?

Mine will loose about 3psi when it sets a month. I wouldn't worry about it at all.

All tires lose air, that is why rvers always check their tires before they take to the road, everyday in some cases. Losing air is normal, and 3 pounds over a month is not that unusual.

I wouldn't worry about it. That much of a change could be temperature related, valve stem leakage, tire seal leakage or even a variance in the gauge you used. What ever the case, 3 psi over a month isn't a big deal.

I wouldn’t consider that as being normal, but acceptable might mean different things to different people…

Normal might be 1 pound over a months’ time under controlled conditions… but also consider the different ambient temps might account for some of the difference making what you see acceptable…