Tyre inflation

The Ring RAC900 is a great bit of kit, with a hose that easily reaches the rear of my MH from the engine comportment. This is where you hook up to your positive and negative terminals. See https://www.youtube.com/watch?v=lB0JL1ebcxk

This shows you how to access your terminals.

The motor home manufacturers always quote the max pressure. If you contact the tyre company and give them the axle weights from your plate, they used to then give you the best pressures for your van. In past posts, a table for calculating tyre pressures was available. 
if you do lower your pressures then your tyre pressure monitors will have to be reset by your local garage. 
ps we did over 170,000 miles on 60/65 and never had a problem with steering or tyre wear. 

The axel weights for the base vehicle will change significantly post conversion, particularly when the original chassis is removed and changed in that process. The only way to obtain true axel weights is to load your van according to your ‘usual’ needs and then take it to a weigh bridge. Once done consult the tyre manufacturer with the newly collected data to ascertain optimum tyre pressures.

Some useful information here on tyre pressures. I am not sure all manufacturers are willing to engage with their customers re changing (especially rear) pressures. I have read that Michelin won't engage, unless that has changed recently?

David

I have used one of THESE for a while now, very handy and charged from any usb port.

You might find THIS useful.

The plate on my Hymer was a Hymer plate with their post build ratings. The Fiat tyre pressure settings were crossed out in the handbook as ‘do not use’. But that was back in 2004!

There is.  Under the bonnet is the +plus and -neg terminals for jump lead connection.  These can be used.  

There is a formula - to be found somewhere on the internet, I suppose - for calculating tyre pressures which takes into account weight of vehicle, tyre size etc.

I found this out by accident because when we took delivery of our present van, the data plate by the door of the van stated that the correct pressure was 65psi.  Although I thought this high for a TA van, on checking the tyre pressures, I saw that they had been set to that level, so assumed it was correct. I continued to run them at this level for two years - indeed that was the main reason I bought the Ring pump because my existing pump wouldn't go that high.

It was by pure chance that I came across a discussion on a forum about tyre pressures that I found out that, in fact, the correct pressure for my van tyres was 43psi and this was eventually confirmed by Knaus.  What's more, on examination of the tyres, I discovered that the maximum pressure to which they should be inflated was 50psi!!

It turned out that, from said forum, I wasn't the only Knaus owner to have the incorrect tyre pressure on the data plate.

Needless to say, a very stern letter was sent to both the dealer and Knaus - pointing out the obvious safety issues of running tyres at such a high level and I ended up with a new set of tyres f.o.c.

Just to point out that manufacturer's information shouldn't always be taken as gospel.

I too have the RAC900 which appears to be a quality piece of kit, so quite surprised to read the negative review above.

I keep a small car battery in the garage at home to connect it to rather than the faff of having to open vehicle bonnets to connect the croc clips. Sometimes on a Sunday afternoon I will just get the RAC pump and my battery out and can check the family fleet of vehicles all in one go.....

My chassis handbook gives tyre pressures for a range of axle weights. Like chasncath I settled for 60psi front 65psi rear.

peedee