Tyre pressure

Rose,

Could you give the full spec of the tyre?  It will be something like 215/70 R15 CP 109R.  It will be embossed on the sidewall of each tyre.  As your's is an older van, the tyres should have been replaced at some time so its worth checking that the spec is the same on all 4 tyres.

Whilst you're at it, just check the tyre pressure label again.  I would expect it to say 5.0 bar front rather than 5.5 bar front.

rose49f wrote:They were all new during covid last year. I will check tyres when l go down later. And will check label tomorrow. So the tyres are too hard then.

You are making me jump the gun before I know the detailed spec of your tyres.  The ETRTO who regulate all tyre manufacturers and Michelin who made your Agilis Camper tyres recommend that regardless of your rear axle mass, the cold tyre pressures of your rear Camping Pneu (CP) tyres are always 5.5 bar, which equates to 79.7 psi which most round up to 80 psi.  So that's half your question answered.  I can also say with complete conviction that if you are running your front tyres at this pressure, they are grossly overinflated.  I'll go further when you give me the detailed spec of your tyres.

rose49f wrote:Yes. Label says 5.5 front and back and tyres are 215/70 R15 CP

I am surprised it says 5.5 bar at the front.  5.5 bar is your CP tyre's maximum permitted pressure which is normally reserved for the rear tyres only.  I also have 215/70 R15 CP tyres on my later 2 berth/seat Nuevo.  Its tyre pressure label says 5.0 bar for the front tyres.  It's possible that in 2006 different front pressures were recommended for CP tyres.  Whatever, 5.5 bar for the front tyres can be ignored.  This is because that high pressure was for when the front axle was loaded to its maximum permitted mass.  Your fully loaded Nuevo's front axle mass will always be well below this.  To determine your correct cold front tyre pressures, you will need to know your fully loaded Nuevo's front axle mass.  This is why the owner of a motorhome should take it at least once during their ownership to a weighbridge to establish what this mass is.  They can also establish that they are not exceeding the maximum permitted mass of the vehicle or its rear axle.  Having established what the front axle mass is, enter this into TyreSafe's on-line calculator for your 215/70 R15 CP 109 tyre. 

https://www.tyresafe.org/motorhome-tyre-pressure/

TyreSafe are sponsored by all the major tyre manufacturers.  It doesn't matter what mass you enter for your rear axle as TyreSafe like the ETRTO and Michelin recommend it should always be 80 psi / 5.5 bar which is the pressure I also recommend you use.

If for example you enter 1450 kg for your front axle mass it will come up with 50 psi /  3.45 bar which is the front pressure you should use.  I am going to guess that your front axle mass will be within 50 kg of this figure but you need to know the actual figure.

If you have been running your fronts at 80 psi / 5.5 bar (because that is on the tyre pressure label), you might be nervous about dropping the pressure by for example 30 psi (37.5%) to 50 psi / 3.45 bar, especially as its much more dangerous for a tyre to be under inflated than over inflated.  It should therefore reassure you to know that the TyreSafe on-line calculator gives the ETRTO pressure for your tyre for an axle mass that is 10% higher.  This is to ensure a degree of over inflation and to compensate for uneven tyre loading across the axle which is always present.  

I hope this is clear and helps.

rose49f wrote:What damage can be done if the tyres are over inflated. I will have a word with my garage when l get back . They look after my van for me and inflated my tyres.

Rose - Cymro has answered it.  Overinflated tyres will wear more quickly in the centre of the tread and will have less grip on the ground.  This can cause increased braking distances, less precise steering and reduced traction e.g. on wet or icy roads and on grass pitches.  They will also give a harsher less compliant ride although increased comfort is not a reason on its own to reduce tyre pressures.  

My motorhome's front tyres were inflated to 5.0 bar when I took it over.  At first I thought nothing of it as that was the figure on Peugeot's tyre pressure label.  It was only after the matter was raised on this Forum and substantial investigation involving MMM, CAMC, NCC, A-S, Bailey, Peugeot, different parts of the DfT, TyreSafe, Continental, Michelin and Pirelli that I determined that my front tyre pressure should be reduced to 48 psi / 3.3 bar to reflect a front axle mass of 1390 kg when my Nuevo is fully loaded for a trip with two in the cab.  With the written support of Continental who manufactured my tyres, the settings on my Tyre Pressure Monitoring System (TPMS) had to be altered by a local Peugeot dealer to allow this and as a gesture of goodwill,A-S paid for the work to be done.

Rose - how often do you take it to the garage?

rose49f wrote:Touch wood not often. MOT service and if l think something is wrong like tyres. This is why they blew them up as looked a soft l thought. Fantastic van. I know how to check oil water etc. And know about funny noises as have always had old cars.

Oh dear.  This is not right.  Sorry but here comes a bit of a lecture but its got to be said.  When a tyre's pressure is checked and adjusted, it must be cold.  This means it must not have been driven on or exposed to direct sunlight for at least 2 hours.  For this reason I doubt that a garage will be able to set your correct cold tyre pressures because the vehicle will have just been driven and possibly in the sun.  From the moment you leave a garage or tyre fitter, the tyres' pressures are your responsibility.  You cannot assume that the garage or tyre fitter has set them correctly.  This morning I have had a new tyre fitted to my car.  Once the tyre has cooled down I will check and adjust its pressure.  It is recommended that drivers check their cold tyre pressures every month and before every long journey.  I use my Nuevo about once a month.  Before doing so I always check the cold tyre pressures.  If I am going on a long trip with multiple long journeys, I also check the pressures during the trip.  All you need to check and adjust tyre pressures is a pressure gauge and pump which I always carry in the motorhome.  If your garage has been advising you to inflate your front tyres to 5.5 bar, they have been giving you bad advice.  The correct advice has been given in this thread.  Determine your fully loaded front axle mass and enter the figure in the TyreSafe on-line calculator.

rose49f wrote:I do trust my local garage having dealt with them for over 40 years and looked after my campers for 10+ years with no problem at all but something was in my brain made me think the  about tyre pressure when l asked the lad to blow up the tyres. Tgis is why l asked.The owner will sort it when l get back.  

Remember that they are mechanics and not engineers and they probably have little or no understanding of motorhome tyre pressures and the ETRTO.