Have you checked the tyre valves?
Check your caravan tyre valves! We were due to go away for a couple of weeks recently so I went over to the storage site to check the van, fortunately a few days before we set off! I found one tyre down to 25psi normally 55, It had been fine earlier and
had not lost pressure for months at a time. The cause was a perished tyre valve. The tyres had been replaced as part of the deal when I purchased the van several years ago but obviously the fitter had not replaced the valves. The moral is make sure the valve
is changed as well as the tyre. I got the valves changed on both wheels as I was not happy to trust the other side. We got away OK and have had a great 2½ weeks exploring Derbyshire and The Yorkshire Dales – brilliant CL near Skipton pitches at least twice
the spacing on a Club site and a picnic bench for each pitch, and soooo quite!