Today my cheap and cheerful Tesco 12v tyre pump decided to fail. The on/off switch gave up the ghost. As I needed to check the MH tyres I bought a Ring RAC 620 clearly advertised by Ring as being able to inflate tyres to 100 psi so okay for my maximum of 80 psi. Not a bit of it; it ground to a halt at 78 psi; useless. I rang Ring tech support. Oh yes they said, we know. It will only inflate cycle tyres to above 80 psi. MH tyres are too big. What you need is the much more expensive RAC 700 or 900. So, if you are thinking of buying a Ring Automotive product take their performance claims with a big pinch of salt and IMHO they are best avoided entirely.