email from Continental .......
It is extremely likely that the relevant information supplied with the chassis is documented for use as a commercial vehicle, therefore proposed before the conversion to a motor home. For this reason, Continental tyres would always recommend having the motor home weighed on a weigh bridge at your heaviest travelling weight, including liquids to achieve specific axle weights. In some cases the coach builder will also put their recommended pressures on the vehicle plate. However, the majority put this to the maximum inflation pressure of the tyre to cover all loads being applied and not specific loads which often, are not near the plated weight you actually travel at.
The volume and pressure of the inflation medium is what carries the load and if it is not sufficient then the tyre can suffer damage, hence why it is extremely important for the correct loads to be obtained, in order to inflate the tyre correctly.
Experience shows that due to the weight distribution of vehicles in the leisure industry such as motor homes the likelihood of overloading or uneven weight distribution tends to put a greater load on the rear axle rather than on the front axles, where the weight tends to remain more consistent. It is true that when braking occurs the weight transference is to the front, but this only tends to be for short periods, whereas overloading on the rear axle can be present over long periods, when the tyres are rotating at high speed.
This is the main reason that with CP Camper type tyres the inflation pressures at the rear is deliberately set higher. Although this also has a bearing on the contact area when negotiating grassy parking areas and also to the sidewall deflection, which influences the body roll.
The 69 psi written on the side of the tyre is for the Northern American market only and the inflation pressure of the tyre can exceed this value within its safety operating range.
Based on the following:
ContiVanco Camper 215/70 R15 (CP*) 109 R tyres.
(*CP- Camper) (Single fitment (S) = two wheels per axle, Twinned fitment (T) = four (or more) wheels per axle)
I have included the chart for these specific tyres to help with pressure vs. load.
I hope this helps and any further enquiries (no matter how small) please do not hesitate to ask, we are always happy to help!
Continental Tyre Group Ltd
DC2 Castle Mound Way
Direct Line: +44 (0)1788 566240
Fax: +44 (0)1788 517731
E-Mail: administrator.technical @conti.de
Web: http:// www.continental-tyres.co.uk