2009 Nuevo Classic - Tyre Pressures

bolero boy wrote:

Caraman wrote:Another drip feed, this time a very important one just received from Continental.  

The ETRTO – the European Tyre & Rim Technical Organisation - stipulate that single axle CP rear tyres must be inflated to 5.5 Bar regardless of the actual rear axle load. This applies to both Michelin and Continental Tyres.

So we have all been misled by Continental into thinking that we can vary our rear tyre pressures in accordance the actual rear axle load.  Those running their single axle rear CP tyres at less than 5.5 Bar should take note.  

noted, and duly ignored, im afraid....they will continue to run at 55 ish and, if questioned, they were obviously 80 when last checked and both have slow punctures...

id be interested to (try and) understand why (apparently) a front set of tyres needs to be inflated in line with axle loadings yet the rears be set at 80 (their max).

its quite possible for a light van to have its rear tyres at twice the pressure of the fronts....

anyone setting up a vehicle (almost any type of vehicle) years ago and given this extreme set up would have thought this was a recipe for handling disaster the 'advisor' had gone mad.

i doubt that Continental have been 'misleading' anyone, but something must have caused them to change their advice....id be interested to hear what that was.

Using the now incorrect rear CP tyre figures which Continental previously provided, 55 psi seems incredibly low as its close to my Nuevo EK's MRO of 1520 kg.  I can't explain adequately why the ETRTO stipulates 5.5 Bar for the rear tyres.  You must ask that question of Michelin and now Continental.

The ETRTO recommended figure applies to CP as single fitment, does not apply to C tyres.

Their latest recommendations are here (March 2019)
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PLOUGHLIN wrote:The ETRTO recommended figure applies to CP as single fitment, does not apply to C tyres.

Their latest recommendations are here (March 2019)
[You must be registered and logged in to see this link.]

Agreed.  This has nothing to do with C tyres.  It's only CP tyres.  Continental has just confirmed that my Nuevo's front tyres with a maximum likely front axle mass of only 1500 kg should be no more than 3.25 Bar.  I can't get down to that pressure without setting off the TPMS which Peugeot will only change if Auto-sleepers re-plates the tyre pressures which currently they won't do hence my DVSA investigation.  1500 kg is significant as when loading a Nuevo EK its nigh on impossible to exceed this figure without exceeding the Nuevo's MTPLM of 3500 kg and rear axle MTPLM of 2000 kg.

Are not these ETRTO statements recommendations not the law of the land!

Tyre pressures are always a compremise.
Too high a pressure could reduce grip.

Micky

mikethebike wrote:Are not these ETRTO statements recommendations not the law of the land!

Tyre pressures are always a compremise.
Too high a pressure could reduce grip.

Micky

We are only talking about the rear wheels/tyres here which on my Nuevo are not driven and the difference between 5.5 Bar and say 5.0 Bar is not great.  The real issue for me is the front wheels/tyres which are driven and directly affect the steering and where the pressure difference is much greater.

Caraman wrote:Another drip feed, this time a very important one just received from Continental.  

The ETRTO – the European Tyre & Rim Technical Organisation - stipulate that single axle CP rear tyres must be inflated to 5.5 Bar regardless of the actual rear axle load. This applies to both Michelin and Continental Tyres.

So we have all been misled by Continental into thinking that we can vary our rear tyre pressures in accordance the actual rear axle load.  Those running their single axle rear CP tyres at less than 5.5 Bar should take note.  

Caraman: I wonder if you could share the context in which you've received this seemingly startling volte face from Continental, please? Sometimes the context of a sentence is significant.

Given that you're in contact with Continental, I wonder if you'd be prepared to ask them whether they now recommend to us motorhome users that we set our single axle Continental CancoCamper CP 215/70R15 CP 109R rear tyres  at 5.5 Bar irrespective of load, or should we adhere to their published table whereby rear pressures vary with axle weight (e.g. rear axle weight 1,755kg should be set at 4.5 bar)?

Secondly, does Continental continue to recommend, as per their table, that front CP (same size) tyres be set according to their table (e.g front axle weight 1,425kg should be set at 3 Bar)?

That would be really helpful. Thank you, Caraman, for persevering on our behalf, with AS, Continental and DVSA.

Cymro

Cymro,

The General Manager of Continental's Technical Services sent me an extract of an ETRTO document providing additional guidance related to Camper Van tyres:

"The LI designation of CP-type tyres carries a single 'load index' indicating their normal use in single fitment.  In this case only, tyres on the rear axle have to be inflated to 550 kPa (5.5 Bar).  (to compensate for severe conditions on unequal load distribution, but with no further concession to increase the maximum load capacity).  When these tyres are used in dual fitment, a tyre pressure increase is not required and the axle load capacity is calculated as 1.85 times that of a single wheel fitment."

He then said "As all tyre manufacturers must comply with this then you should inflate your rear tyres to 5.5 Bar.  My sincere apologies for any confusion this may have caused."

I then asked him a supplementary question about the front axle/tyres.  He replied stating "based on a likely mass of 1500 kg (this was a figure that I provided) I would recommend a front inflation pressure of 3.25 Bar (47 psi)."  

Similar information about the rear tyre pressure of 5.5 Bar is given by Michelin.  They also recommend that the tyre pressures used should be those recommended by the vehicle manufacturer i.e. the plated figures which clearly Continental do not agree with.

As I am sure you are aware, Continental are very responsive and helpful when you ask them questions through their website [You must be registered and logged in to see this link.]
If you or anyone else has questions or doubts about any of this I recommend they contact Continental.

I know and you know that these camper tyres are 'recommended' by the manufacturers to be inflated to 5.5 bar on the rear but what about the less experienced buyers who buy a secondhand van already fitted with such tyres. They will inflate to either the vehicle handbook or the door post sticker. When these tyres are fitted, shouldn't the tyre fitter company be responsible for putting a sticker explaining the need for higher pressures otherwise who can blame owners for running on standard pressures. If stopped by police on a routine check, would the police know they were under pressure, they too would more than likely use the door pillar figures.

My motorhomes have all been  on C rated tyres. No problems and easy to use a chart for tyre pressures after weighing.
This problem ONLY RELATES to the CP rated tyres.
Does your tyre plate or handbook specify CP Tyres?

Are all new motorhomes fitted with CP tyres?

Answers would help as i believe most motorhomes are on C rated tyres.

thank you


Micky

I bought the Sussex secondhand with Michelin Camper Agilis tyres already on. The previous Nuevo also had Michelin Camper Agilis fitted (also secondhand). None were original tyres from new. 
If i look for new tyres on etyres then Camper tyres come up as a suitable tyre when I enter registration number. There is no warning as to required pressures.

The general advice I am picking up is that tyre pressures should be those recommended by the tyre manufacturer so if you change to a non-standard tyre i.e. one that was not part of the vehicle's original specification, you should find out from the tyre manufacturer what pressures to use.  The DVSA gave me some initial and interesting advice on plated figures which they are investigating further:

"I can confirm that the Plating and Testing regulations only apply to commercial Goods vehicles over 3500kgs. Goods vehicles and Motor Caravans (which are not considered to be Goods vehicles at any weight), less than 3500kgs are therefore not subject to these regulations. Therefore, if the only reason the TPMS system is not being adjusted is because the company believes the vehicle should be plated, I can confirm that this is not the case."

Cymro, yes im sure that is what is now being recommended...
Fronts based on axle weight and rear always set to the max.
Michelin have been advocating this for quite a while (probably based on the ETRTO advice) whereas Continental have (up until now) recommended using the axle weight for each axle pressure level.
Continental have indeed seemed to have changed their advice regarding the rears.
As i mentioned above, its perfectly possible to have a well balanced van with axle loads of (say) 1600 Kg on both front and rear.
using the ETRTO guidelines the fronts would be 3.0 bar/ 43.5 psi
while the rears would be 5.5 bar/ 80 psi. almost twice the setting.
moving in the other direction, a van could have its rear end loaded to the max of 2000kg and also have 5.5 bar in the tyres.
im wondering how a 400kg difference (or more) can result in the same recommendation?
i guessing something to do with a 'cover all eventualities' statement where its assumed owners DONT weigh their vehicles and 80 psi allows for those that run their vans at the max.
However, my view is that those owners who dont bother to find out what their vans weigh arent likely to check what pressures are needed from a door pillar....in fact, there will ne many who probably never check/inflate the tyres at all....
so, the figures on the pillar default to becoming info for the service team at service time....if those owners bother to get the van serviced.
conclusion, the 80 psi is a catch all to cover as many bums as possible....

Yes indeed, Bolero Boy. 

But the consequential issue is that which Caraman has identified: if we follow the latest guidance, and now set our rears at the mandatory 5.5bar / 80psi and set our fronts according to axle load (let's say 3.0 bar / 44psi) then the TPMS as calibrated by Peugeot will be triggered by the low front pressures - the Peugeot factory setting being 5.0 bar in the font.

And here's the rub: Caraman (and probably others) cannot persuade their Peugeot dealer to reset the TPMS to accommodate the recommended lower tyre pressures. 

I was lucky: my dealer complied with my request, albeit that they pointed out in writing that my requested settings were lower than those recommended by Peugeot. By today, it seems that attitudes have hardened, leaving owners in what could be the dangerous position of being forced to run on over-inflated front tyres.

Let's hope DVSA can induce some common sense....

Cymro

I have just visited the Continental site.
   
    1)    I believe CP tyres ,which are recommended for heavy camper vans & rough camping ,have always recommended higher pressures.
2)    Continental vanco 2 for light truck tyres up to 3,500  are   C    rated.

 for    example   215/70 r15c  a common tyre, is   109/107  8ply
112 mph speed rating
load rating  index
 109     2271lbs
107      2149 lbs
I am sure most if not all motorhomes under 3,500  are safe with these tyres.
However may have problems with factory fitted tyre pressure devices.

regards

Micky

Micky, my tyres are definitely CP Vancos, and this was what Continental's original (only one to me) recommendation was based on.

RE: the TPMS issue, i saw an article in MMM this month from Ian Pedley who owns a Swift Rio and has written a few times about his mods/upgrades....
this month it was a TPMS system for less than £20. its four simple blutooth caps that screw onto the wheel and transmit the pressures to a simple console....they are on ebay now.
although i dont have a factory fit system (so no resetting issues) id certainly ditch the Peugeot one and fit one of these cheap ones.

MikeTheBike,

I think you'll find that  Continental have not always recommended high pressure for CP tyres. In 2015 I downloaded Continental's chart, for 215/70R15 CP 109R tyres (as fitted to my then new Nuevo). It shows 11 sets of pressures, depending on 11 different axle weights, for front tyres, and another matrix of 11 for rear tyres. The pressures in the chart for that tyre range from 44psi (front, with lightest load) to 69psi (front, heaviest) and from 44psi (rear, lightest) to 80 (rear heaviest).

Using my measured axle weights, I should be running on 44:75, but in fact I run at 53:75 (because I'm wary about a difference of 31psi between front and back - albeit that my old beetle had a similar disparity, proportionally).

I am content with 53:75.

Cymro

Cymro.   Thanks.
Its a minefield.  
It also has different presures depending on driving wheels.
Has anyone got a sticker or something in writing about CP tyres when they purchased?

Glad i have C rated tyres.
My 3,500  Autotrail ,front wheel drive ,is running on 65 F and 70 R.
No way would i run with massive difference between axles.
44/80 on a front wheel drive is to my mind unsafe.even with heavy duty CP tyres.
remember it is always recommended to fit new tyres to the rear, i think,to do with
Rear wheel breakaway  risks.

 Micky
.

I have discovered a little more about tyre pressures from Continental and from TyreSafe which is sponsored by the major tyre manufactures.  All tyre pressures are set by the ETRTO which all tyre manufacturers must use.  As reported above for CP tyres, the rear tyre pressures of single axle/fitment motorhomes, regardless of the rear axle mass, is fixed at 5.5 bar which equates to about 80 psi.  

The maximum the front CP tyre pressure can be is 4.75 bar which equates to about 69 psi.  This pressure is for the the maximum permissible mass on the tyre of 1030 kg or 2060 kg for the axle. This is the starting point used by the ETRTO to derive the minimum pressures for lower front axle masses.  I don't know where Peugeot got its front CP tyre pressure of 5.0 bar from.  TyreSafe use the ETRTO baseline figures in their online calculator which can be used for 'CP' and the lower spec 'C' tyres.

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TyreSafe use a ETRTO pressure for an axle mass 10% higher than the actual mass, up to the maximum permitted mass on the tyre.  This is to help offset uneven loads across an axle, inaccuracies in axle weighings and extra weight added before going on a journey etc.  So the TyreSafe pressure figures are more conservative than the ETRTO baseline figures used by Continental.

Using TyreSafe's more conservative figures it can be seen that a Nuevo EK with a front axle MRO of 1304 kg should have its front CP tyres set at 44 psi (3.02 bar).  As the Nuevo EK is progressively loaded its rear axle MTPLM of 2000 kg will be reached when or before its front axle mass reaches 1500 kg, so the highest the front CP tyres should be is 52 psi (3.6 bar).  In normal use the front CP tyre pressures of a Nuevo EK should be somewhere between 44 psi and 52 psi.  Auto-Sleepers Peugeot coachbuilt luton models will have a higher MRO so their minimum pressure will be higher than 44 psi but I suspect the upper figure of 52 psi will be much the same as the low profile models.

Thanks for this authoritative post, Caraman. I think Moderators should paste it as a "sticke" or whatever, so that it can be easily consulted.

Of course, that information about the front tyres exposes the problem about Peugeot dealers' inflexible attitude to requests to lower the trigger pressure for the front TPMS. As you've pointed out, how can we run our fronts at, say , 3.5 bar when the TPMS will be triggered if the pressure is below 5.0 bar?  Let's await the DVSA's ruling.....

Cymro

Not sure this is the definitive answer.
Tyre pressures for front wheel drive vehicles are different.
That tyresafe  site   is  for rear wheel drive vehicles.IMHO
It also says do not exceed tyre pressure figure on the tyre .
That is usually 79 psi.
However that is for the USA requirement.

I still see this as a CP tyre problem .


Micky

mikethebike wrote:Not sure this is the definitive answer.
Tyre pressures for front wheel drive vehicles are different.
That tyresafe  site   is  for rear wheel drive vehicles.IMHO
It also says do not exceed tyre pressure figure on the tyre .
That is usually 79 psi.
However that is for the USA requirement.

I still see this as a CP tyre problem .


Micky

Could you point to where the tyresafe website says it's for rear wheel drive?

mikethebike wrote:Not sure this is the definitive answer.
Tyre pressures for front wheel drive vehicles are different.
That tyresafe  site   is  for rear wheel drive vehicles.IMHO
It also says do not exceed tyre pressure figure on the tyre .
That is usually 79 psi.
However that is for the USA requirement.

I still see this as a CP tyre problem .


Micky

My 2019 Nuevo EK has a MRO of 1304 kg front axle, 1520 kg rear axle and 2824 kg overall - these figure are provided by Auto-Sleepers.  Using my Nuevo as an example, TyreSafe recommend that when driven at its MRO the tyre pressures should be 44 psi front and 80 psi rear if the Camper (CP) tyre is fitted or 41 psi front 50 psi rear if the cheaper Light Commercial (C) tyre is fitted which is not recommended.  If anyone believes these pressures are only for rear wheel drive motorhomes or that in the case of the CP tyre having a difference of 36 psi between the front and rear tyres is unsafe, put these assertions to TyreSafe on their contacts page and see what they say.

Paul. Thats one problem ,it does not differentiate  between front and rear wheel drive.
The  chart we used from Continental did.
My opinion is this upgrade to a heavy duty tyre was initially for rear wheel drive.
We now have front wheel drive vehicles using these tyres. 

44 front 80 rear seems to me to be difficult to believe advice for a front wheel drive vehicle.only 200 kgs different between axles and only 2824 total.
I have only looked or used Tyre manufacturers charts.
Who is this tyresafe  authority.?

My last motorhome was a Mercedes rear wheel drive.I will look up my records as to my tyre pressures used.

I would expect the ride on a small motorhome  with these pressures to be uncomfortable as well.
the back tyres could be jumping all over the place  on some roads.

My  personal views ,but if you feel safer with those  cold high pressures use them.


Micky

Tyresafe.  Its a registered charity. It says go to your manufacturer or tyre dealer  first.

It has a long list in its disclaimers. So if advice is wrong you are on your own.

I would use a tyre company for advice.

Micky

mikethebike wrote:
I would use a tyre company for advice.

Micky

I have used the tyre company for advice several times.  Their advice is to use the latest 2020 ETRTO figures which is what TyreSafe also do except they increase them slightly in the way I described.  It doesn't matter whether you go to the tyre manufacturer or TyreSafe for advice, they all sing off the same ETRTO hymn sheet.  The advantage of using the TyreSafe online calculator is that it gives a pressure for any axle mass and it plays safe by adding on a bit up to the maximum of 4.75 bar for the front CP tyre.  I haven't investigated the maximum for the C tyre.  When I received CP tyre pressure advice from Continental they knew my base vehicle was a FWD Peugeot Boxer.  I have seen nothing that suggests that the ETRTO figures that Continental or TyreSafe are using are only for RWD motorhomes.  If this was the case it would be made very clear and there would be a separate set figures for FWD motorhomes.