Technical Motorhome-Van tyre pressures

[Steve928]

As I understand it CP (Camping Tyres) have stiffer side walls to better cope with a lot of time spent not moving and the generally higher basic weight of MHs

Oft repeated but not the case; a CP carcase supports a higher pressure than a C carcase and it is this pressure which supports the motorhome weight, rolling or stationary. The only tyres that I know of where the sidewall construction is designed to carry weight are car runflat ones.
A Michelin Agilis CP tyre for example, being one of Michelin's GreenX low rolling resistance tyres, has one of the 'floppiest' sidewalls you're likely to encounter on a tyre in that size. I once cut cross sections of a Michelin Agilis CP and a comparable C tyre (I recall it was a Falken Linam R51) and the C tyre's sidewall was markedly thicker and stiffer - designed perhaps to survive white van man driving it up kerbs..

 

[VinceS]

Thanks for the info that is interesting, I looked at Michelins website which just said CP tyres had a stronger carcass for longer standing.
Continental say : If you drive a heavy camping vehicle, then we’ve got a very strong tyre for you. We managed to strengthen the construction and make it less sensitive to heavy loads – according to Camping Pneus (CP) standards

So basically stronger carcass?

 

[Steve928]

Yes, I believe so; built with a carcass that can contain/withstand a higher pressure than C tyres and thus support a given weight with less sidewall deformation.
(But suffer from poor grip due to the reduced contact patch, give an awful ride and have a tendency for the rubber to crack over time - otherwise all good )

 

[tribune123]

Contact tyre manufacturer technical department with axle loadings. They will
tell you what pressures the tyres require. I fitted Toyo tyres and they recommended
50 psi front 45 rear. Ignore pressures on door post, miles too high.