Michelin camping tyre pressures

[Leo Valentino]

F.Y.I

Just noticed the tyre pressures on my new motorhome on the actual tyre have changed from 80psi now shown as 475kPa which according to my reckoning is a drop of about 11psi.

Definitely a step in the right direction.

Anyone noticed this!.

[Agaric]

The Michelin UK website still has 4.5 bar front and 5.5 bar rear. That 475 kPa is that for the front or rear.

[Derek Uzzell]

In 2019 Michelin’s advice for their “Agilis Camping” tyres was as given here

 

https://www.motorhomefun.co.uk/forum/threads/michelin-agilis-tyre-pressures.193967/

 

Historically - for many years - the advised pressures for Fiat-based new motorhomes fitted with Michelin and Continental ‘camping-car’ tyres has been 5.0bar(front) and 5.5bar(rear) for 15” tyres, or 5.5bar(front) and 5.5bar(rear) for 16” tyres. However, a lower-than-5.5bar value may well appear on the tyre’s sidewall.

 

475kPa = 4.75bar, but I can’t see that being particularly relevant if (say) Fiat is advising that higher inflation pressures should be used and the motorhome converter is saying the same thing.

[Leo Valentino]

Hi

The 475kPa is quoted on the new tyre alongside the 116Q which in my mind means that is the maximum weight and pressure which is lower than the tyres on my present M/H. Take delivery of new one next Thursday so will see what pressures are quoted on the vehicle.

Just thought it interesting that maximum pressures dropped.

[Derek Uzzell]

I believe your new motorhome is a Burstner Lyseo TD Harmony Line 745 model, built on a Fiat Ducato ‘heavy’ (Maxi) chassis (4250kg GVW) with 16”-diameter alloy wheels.

 

The most recent on-line Fiat Ducato Owner Handbook indicates that - for the Maxi Tempo Libero (camping-car chassis) version - the tyres will normally have a 225/75 R16 CP 116/114Q specification, and advises a cold inflation-pressure of 5.5bar (front) and 5.5bar (rear) for ‘camping tyres’ with that specification.

 

It’s interesting that a kPa value is shown on your tyres, as psi or bar have been used historically for tyre inflation-pressure and most people are familiar with one or the other (or both). My 2015 Rapido’s Michelin Agilis Camper tyres (215/70 R15CP) are marked

 

109Q

at 80PSI

 

I notice that Wikipedia says

 

The pascal (Pa) or kilopascal (kPa) as a unit of pressure measurement is widely used throughout the world and has largely replaced the pounds per square inch (psi) unit, except in some countries that still use the imperial measurement system or the US customary system, including the United States.

 

I have a feeling that Continental’s VancoCamper ‘CP’ tyres had a sidewall inflation-pressure marking (a US requirement) that was less than the 80psi/5.5bar that the tyre could be inflated to, and Continental’s databook entry for a 225/75 R16 CP 116Q tyre gives a 4.75bar inflation pressure value for a front axle load capacity of 2500kg (Load Index = 1250kg x 2), with a 5.5bar value for a ‘single wheel’ rear axle load capacity of 2500kg.

 

You might want to take this up with Michelin as a) if you are maintaining that 475kPa is the maximum pressure your Michelin tyres should be inflated to and b) it’s probable that Fiat and Burstner will advise that 5.5bar (550kPa) be used front and rear for your motorhome’s tyres, there’s an obvious conflict.

[Deneb]

Any tyre pressure markings on a tyre's sidewall are for North American legal requirements only. They do not signify the tyre manufacturer's pressure requirements for European use, nor should they override specific requirements stipulated by the manufacturer of any vehicle to which the tyre may be fitted. The pressures shown will quite likely differ from those required by the European ETRTO/EEC standards.

 

If the load index on your new tyre is lower than your previous tyre, then it stands to reason that the (US DOT) pressure marking will also be lower, since the inflation pressure of a tyre (together with its construction) determines its load rating. Michelin Camping tyres are made in several size and load ratings including 116Q and 118R for the 225/75 R16 tyre. The tyre with a 118R load rating will almost certainly have a higher stated US/DOT maximum inflation pressure than the 116Q version, as the higher pressure will in part determine the tyre's load bearing ability. Similarly, the maximum load capability of the tyre will be lower than that stated on its sidewall if you choose to reduce its inflation pressure from that recommended.

 

I would be more concerned as to whether you have chosen a tyre compatible with the maximum permitted axle weights of your vehicle.

[Derek Uzzell]

Deneb - 2020-07-03 2:34 PM

 

...I would be more concerned as to whether you have chosen a tyre compatible with the maximum permitted axle weights of your vehicle.

 

I don’t think that will be a problem...

 

An example of Leo’s new hand-over-next-week Burstner motorhome is advertised here (with lots of photos)

 

https://www.cranham.co.uk/vehicle-details/Burstner-Lyseo-TD-Harmony-N843/

 

The 745’s Gross Vehicle Weight (GVW) is 4250kg. For the Maxi Tempo Libero (camping-car) chassis on which the Burstner is built, the most recent Fiat Ducato Owner Handbook only gives one tyre specification - 225/75 R16CP 116/114 Q - and that applies for a GVW (or “PAYLOAD” in Fiat-speak!) of 3500kg, 4000kg, 4250kg or 4400kg.

 

I was under the impression that a CP-marked tyre could not carry a load-index ‘dual marking’ - so there would be no 116/114 CP-marked tyre, just a 116 tyre - but that’s ultra-fine detail. Michelin’s Agilis Camping tyre in 225/75 R16CP size is evidently marketed with a 116 Q or a 118 R spec, but it appears that the latter is not fitted as orignal equipment to current Ducatos that have a camping-car chassis.

[Deneb]

Yes Derek, I missed the fact that the tyre was on a new van. I thought Leo was commenting on a new tyre that he'd bought to replace an existing one, and had noticed different load and pressure markings.

 

Even so, on a Maxi chassis with a possible 2500kg permissible rear axle weight, Fiat have gone for the bare minimum by fitting a 116 rated tyre.

[Derek Uzzell]

Yes, it is a mite odd when a 118 load-index tyre is available.

 

This link

 

https://www.fiatprofessional.is/model/ducato-conversion/

 

quotes ‘Maxi Cab’ maximum permitted axle loads of Front axle: 2100 kg and Rear axle: 2500 kg, so theoretically OK for a motorhome up to 4400kg GVW (2100+2500=4600).

 

But the tyre's load-index has tended to exceed a motorhome’s highest maximum axle load, as the 109 load-index (2060kg axle load) exceeds the rear axle maximum of 2000kg when 15” wheels with 215/70 R15CP tyres are fitted to a Ducato ‘light’ chassis.

[Deneb]

Agreed, I would always prefer to see an additional margin for safety, albeit the choice is perfectly legal.

[Agaric]

It seems quite a bit different to the advise that Michelin USA give for RV tyres, different weight different pressures and non CP tyres, just the crossclimate though its ratings are the same for CP tyres.

 

Here, https://www.michelinrvtires.com/reference-materials/load-and-inflation-tables/#/

 

My Hankook tyres which were fitted to my MH recomended a pressure of 65 psi at 1900kg on the rear in the US they were rated for 2060kg at the same pressure.

 

[Derek Uzzell]

This May 2020 forum thread discussed inflation-pressures for Continental “VancoCamper” tyres

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Continental-Vancampo-Tyre-pressures/55287/#M649498

 

and I notice that (as I touched on above) the sidewall ‘pressure marking' on those tyres was said to be 69psi, though the pressures advised on the motorhome’s door were higher.

 

Trying to relate the USA tyre scene to the European one is like comparing American football with rugby - it’s a different ball-game.

[colin]

Agaric - 2020-07-04 7:06 PM

 

It seems quite a bit different to the advise that Michelin USA give for RV tyres, different weight different pressures and non CP tyres, just the crossclimate though its ratings are the same for CP tyres.

 

Here, https://www.michelinrvtires.com/reference-materials/load-and-inflation-tables/#/

 

My Hankook tyres which were fitted to my MH recomended a pressure of 65 psi at 1900kg on the rear in the US they were rated for 2060kg at the same pressure.

 

The joke is, in Europe Michelin won't recommend CrossClimate's for campervans, when I corresponded with Michelin over tyres for my van they got their knickers in a twist over it, they would be happy for me to run the same van as a commercial at 4t, but not as a campervan at 3.5t.

[Derek Uzzell]

Michelin rigidly follows the ETRTO's 2013 advice that includes the statement

 

"For these reasons, it is strongly recommended that motor-caravans are only fitted with CP-tyres."

 

As their Cross-Climate tyres are not CP-marked, Michelin will feel 'compelled' to advise that these tyres are not fitted to motor caravans, though they can, of course, be fitted to equivalent weight (or heavier) 'white vans' as that won't conflict with the ETRTO's guidance.

[colin]

Last time I looked there where no 215/75-16 10ply CP tyres, there where a couple that are named 'Camper' but did not carry the CP, has this changed, or do I have to run my van on the rims.

[Derek Uzzell]

Possibly the most suitable tyre for motorhomes nowadays is Continental’s “VanContact Camper” pattern that is an ‘all season’ tyre with M+S, 3MPSF and CP markings. However - according to this advert

 

https://tyres.rezulteo.co.uk/continental/vancontact-camper

 

it is only available with the following four specifications

 

225/70 R15 112S

225/75 R16 118R

235/65 R16 115R

255/55 R18 120R

 

Continental’s “VancoCamper” (that has been around for quite a while) is apparently available with a 215/75 R16 116 R specification. This advert indicates that this makes the tyre ‘10PR’

 

https://www.tyres-pneus-online.co.uk/car-tyres/continental/vanco-camper/215-75-r16-116-r-10-pr.html

 

though it’s perhaps worth mentioning (as the ‘i’ in the advert highlights) that this archaic rating method has no direct relationship to the number of plies in the tyre’s construction.

 

My understanding is that the CP-marking may only be used on 8PR tyres (I assume this is a weird ETRTO diktat) so the 215/75 R16 116 R VancoCamper does not qualify. Nevertheless it is a genuine camping-car tyre. Unlike “VanContact Camper” it’s designated a ’summer’ tyre and is not M+S, 3MPSF, nor CP marked.

[Leo Valentino]

Derek

Yes you are correct re our new motorhome. Didn't realise the tyre markings were for North America and not found much about them on the internet.

 

My thoughts are if the tyres are good to carry the weight there inflated at 4.75 then why do we need to inflate to 5.5 and suffer a very harsh ride.

 

Will let you know what pressures are quoted for the vehicle when we get it.

 

Thank you Steve

[colin]

Derek Uzzell - 2020-07-05 1:39 PM

 

Possibly the most suitable tyre for motorhomes nowadays is Continental’s “VanContact Camper” pattern that is an ‘all season’ tyre with M+S, 3MPSF and CP markings. However - according to this advert

 

https://tyres.rezulteo.co.uk/continental/vancontact-camper

 

it is only available with the following four specifications

 

225/70 R15 112S

225/75 R16 118R

235/65 R16 115R

255/55 R18 120R

 

Continental’s “VancoCamper” (that has been around for quite a while) is apparently available with a 215/75 R16 116 R specification. This advert indicates that this makes the tyre ‘10PR’

 

https://www.tyres-pneus-online.co.uk/car-tyres/continental/vanco-camper/215-75-r16-116-r-10-pr.html

 

though it’s perhaps worth mentioning (as the ‘i’ in the advert highlights) that this archaic rating method has no direct relationship to the number of plies in the tyre’s construction.

 

My understanding is that the CP-marking may only be used on 8PR tyres (I assume this is a weird ETRTO diktat) so the 215/75 R16 116 R VancoCamper does not qualify. Nevertheless it is a genuine camping-car tyre. Unlike “VanContact Camper” it’s designated a ’summer’ tyre and is not M+S, 3MPSF, nor CP marked.

 

My Globecar came with Continental tyres but as per the regs they are marked 'C' and not 'CP', you might note from the photo's in 'spare wheel removal' thread the WildAx has Continental VanContact 100's, which it came out the factory with.

[Derek Uzzell]

Leo Valentino - 2020-07-05 2:41 PM

 

Derek

Yes you are correct re our new motorhome. Didn't realise the tyre markings were for North America and not found much about them on the internet.

 

My thoughts are if the tyres are good to carry the weight there inflated at 4.75 then why do we need to inflate to 5.5 and suffer a very harsh ride.

 

Will let you know what pressures are quoted for the vehicle when we get it.

 

Thank you Steve

 

This link is to Continental’s 2017.2018 Technical Databook

 

https://blobs.continental-tires.com/www8/servlet/blob/585550/e0854f2c7866c64da551474b998ef8b3/download-technical-databook-data.pdf

 

Pages 86 and 87 provide data for a tyre with a 225/75 R16CP specification and you’ll note (on Page 87) that - for the 116 R variant - three sets of inflation-pressure(bar) to load-capacity(kg) values are given.

 

Those pressures relate to

 

- the front axle of a vehicle where that axle has a single-wheel at each end (FA S)

- the rear axle of a vehicle where that axle has a single-wheel at each end (RA S)

- the rear axle of a vehicle where that axle has twin wheels at each end (RA T).

 

You’ll see that, in the 1st case (FA S), the tyre’s maximum axle-load capacity of 2500kg is related to an inflation-pressure of 4.75bar, whereas, in the 2nd case (RA S) the 2500kg figure relates to a pressure of 5.5bar. Basically - as one might perhaps expect - for a CP-marked tyre aimed at motorhome usage, for a given axle-loading a higher inflation-pressure is advised when the tyre is fitted to the vehicle’s rear axle.

 

Michelin used to publish a light-commercial vehicle data booklet containing similar information to Continental's, but I don’t think it’s still freely available to the general public. This used to say the same thing - for ‘camping-car’ tyres and for a given axle-load, the tyres on the rear axle should be inflated higher than the tyres on the front axle.

 

(Obviously you don’t HAVE to inflate your motorhome’s Michelin tyres beyond the 475kPa shown on the tyres’ sidewall, even though it’s near certain that a 5.5bar (550kPa) pressure will be advised in your motorhome’s handbooks for both front and rear tyres. But, if you do as is regularly suggested on motorhome forums and provide the tyre manufacturer with weighbridge axle-load figures, you should anticipate that Michelin will quote a ‘no choice’ 5.5bar pressure for your motorhome’s rear tyres.)

[Derek Uzzell]

colin - 2020-07-06 12:09 AM

 

My Globecar came with Continental tyres but as per the regs they are marked 'C' and not 'CP', you might note from the photo's in 'spare wheel removal' thread the WildAx has Continental VanContact 100's, which it came out the factory with.

 

20 years or so ago, when Michelin began to market the “XC Camping” range of tyres targeting the motorhome market, there was a liaison between Fiat and Michelin, with Fiat offering a "Camping-Car Package” (CCP) comprising specialised spring-units/dampers and XC Camping tyres. The CCP applied to coachbuilt designs, but NOT to panel-van conversions (PVCs).

 

This liaison persists today, with coachbuilt motorhomes built on a Citroen/Fiat/Peugeot base almost always having CP-marked ‘camping-car' tyres (Michelin or Continental, though Pirelli also makes CP-marked tyres), but PVCs built on a Citroen/Fiat/Peugeot base usually retaining whatever make of C-marked ‘white van’ tyre the factory happened to be fitting at the time.

 

Coachbuilt motorhomes not built on a Citroen/Fiat/Peugeot base have also tended to have C-marked rather than CP-marked tyres (my 2005 Ford-based Hobby for example). However, that’s not a hard-and-fast rule as it's become a buyer expectation (at least outside the UK) that a new coachbuilt motorhome should have CP-marked tyres as standard irrespective of the base vehicle’s manufacturer.

 

Another (in my view) reason why PVCs (at least Continental built PVCs) tend not to have CP-marked tyres is that they are considered to be a different breed to ‘camping-cars’/motorhomes, so ETRTO rules don’t apply to them.

[Keithl]

Derek Uzzell - 2020-07-06 7:59 AM

Michelin used to publish a light-commercial vehicle data booklet containing similar information to Continental's, but I don’t think it’s still freely available to the general public.

 

Derek,

 

I have a link to a 2011 USA Michelin tyre data book which has some useful data but note the USA call 'C' tyres 'LT' for Light Truck.

 

Relevant data is around page 18... https://www.michelintruck.com/assets/pdf/Truck_Tire_Data_Book_Sept2011.pdf

 

Keith.

[Robinhood]

Ithink the discussion has probably already ranged rather too far.

 

It would be interesting to see the actual wording applied to "Camping Car" tyres in the ETRTO standards manual - unfortunately I haven't managed (as yet) to find a free download of the same. The manual is available as a chargeable document.

 

Just to set straight some of the history, however, and to add to the confusion, when 'vans started to become available with the "camping car" package (potentially uprated suspension and CP tyres) I had correspondence with Michelin about the appropriate tyre pressures for two of my 'vans.

 

At that time, they were happy to quote "custom" pressures for both front and rear axle loads, if shared, and with confirmation that this was at the actual fully loaded state.

 

As I understand it, their practice at the time was to quote in line with similar profile "C" tyres (not CP") with the quoted pressures raised by 10% for the front axle to allow for weight transference under heavy braking.

 

I still have part of the correspondence with them from 2001, and all of it from 2004. The quoted pressures for example for 215/75/16CP at my requested axle loadings tallies exactly with the current Conti advice for the same profile "non-CP" tyres, with the 10% added to the front.

[Derek Uzzell]

The CP-marking was discussed in some depth within this 2014 forum thread

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/New-tyre-blowout/33821/

 

In 2014 I asked Michelin exactly what the ETRTO standards manual said about the “CP” suffix. By sheer chance, having not found Michelin’s reply in my email inbox (that I prune regularly and savagely) I came across it lurking in my email ‘Sent' folder.

 

Michelin’s reply was

 

Dear Mr Uzzell

 

Based on page 28 of the ETRTO standards manual 2013, the suffix "CP", meaning Commercial vehicle tyres for service on motor caravans, has no specific regulation but is merely a marking which defines the tyre as a motorhome specific tyre designed to be capable of taking the higher loads often found on motorhomes.

 

The "CP" marking is merely a designation to enable the tyre to be identified as a motorhome tyre as opposed to a "C" marked van tyre or even a car tyre of the same size.

 

Regards

xxxxxxxxx

Consumer Contact Team

 

I’ve also found a 2004 Michelin “Van Tyres Fitments, Pressures and Technical Data” booklet (that I thought I’d chucked away). This provides inflation-pressure-to-axle-load values for each tyre size and the data are identical for Agilis 81 ‘white van’ tyres and “XC Camping” ‘motorhome' tyres that have the same specification. The only difference is that each “XC Camping” entry has a footnote “For maximum load conditions when used on mainland Europe it is recommendedthat the rear tyres are inflated to a pressure of 80psi”.

[Robinhood]

As I said, it's probably been discussed to death, but I was most interested in the wording of ETRTO's recommendations for Motorcaravan tyres, not some interpretation of it by either individuals or manufacturers.

 

I've now found a downloadable version of the 2023 recommendations here:

 

http://pneusnews.it/wp-content/uploads/2014/07/2013-ETRTO-RECOMMENDATIONS.pdf

 

...and, for anyone who doesn't want to trawl through it, the bit I was interested in is this:

 

===

 

Tyre use and maintenance for motor-caravans (or motor homes)

 

Fit the right tyres

 

As with all road vehicles, it is essential that tyres of the correct type be fitted. Tyres usually fitted to motor-caravans are of a "light commercial (“'C”' or “CP”)" type. CP type-tyres (commercial vehicle tyres for service on motor-caravans) have only been marketed in the last few years. This followed a study which demonstrated, that overloading is generally the main cause of tyre failure, due to the fact that this type of vehicle often carries an excessive or badly distributed load, which, may be higher than that permitted by the load index (LI) of the tyre; usually on tyres fitted to the rear axle.

 

CP-type tyres have been designed to cater for the higher loads imposed by motor-caravans, especially when fitted in single formation on the rear driven axle (also see following comments below referring to the “service description”). It is always advisable to have the same type of tyres on all wheels and axles. Only tyres of the same size and service description (load index / speed symbol) and identical wheels should be fitted across an axle and carried as a spare. Tyre pressures across an axle should be equal. additionally, any deviation from the original type of tyre is likely to have an effect on the handling and general characteristics of the vehicle. For these reasons, it is strongly recommended that motor-caravans are only fitted with CP-tyres.

 

Therefore, before changing the type of tyres, always consult either the vehicle or the tyre manufacturer.

 

When fitting any new tyre size differing from the original equipment, it is the users’ responsibility to ensure compliance with existing regulations, regarding specifically, the vehicle’s load and speed capability. Never replace tyres with those of a lower speed rating or lower load capacity.

 

=====

 

There is some "motherhood and apple pie" text afterwards, which does include advice to use the pressures in the vehicle/chassis handbook.

 

The wording rather supports the theory I've always had; that the tyre manufacturers introduced a tyre with inherently greater capacity (at the raised pressures) than one might be led to believe from the load index in order to compensate for the endemic overloading of motorhomes, particularly the rear axle, thereby attempting to circumvent the reputational damage from having repeated tyre-failure on such vehicles. (a quick review of the contents of the "garage" of most continental 'vans rated at 3500kg MAM should reinforce the view that this is a major problem).

 

It's also interesting to note "Tyres usually fitted to motor-caravans are of a "light commercial (“'C”' or “CP”)" type." (despite any later recommendation of "CP"), and the implication that the implementation of CP tyres has been particularly oriented towards vehicles with driven rear wheels.

 

Whatever, there is little there that convinces me that, for a reasonably balanced vehicle with axle loadings well within the load index of the tyre, there is a need to run with the tyre-pressures at the filling-threatening maximum. Others might (quite validly) feel differently. Based on real weighbridge figures, however, I shall continue to run at pressures dictated by the tables for similar profile non-CP tyres, plus a margin of around 10%.

 

I was also amused to note that the FIAT CoC for my 'van shows homologation with 225/75 R16C tyres (front and rear axle, though I doubt it actually left the factory with a rear axle :-) ) The intermediate Al-Ko CoC has homolgation with a plethora of sizes, in both "C" and "CP" versions, and the Hymer CoC is again homologated with 225/75 R16C tyres, but slightly different spec to the Fiat CoC.

[Agaric]

Dribs and drabs of information that have come my way is that CP tyres have an extra toughening in the sidewall to cope with the greater leverage ratios on the rear axle with extended chassis on Motor Homes compared to vans.

 

My last post re: USA website, further to that the tyres quoted Agilis Crossclimate are French made so are the same tyres as in Europe.

 

My front tyres on my MH that I changed last September were Hankook and run at 52 psi with a 1600kg axle weight, removed when they were down to 3mm. They were measured at 4 points across the tyre and 4 points around, so 16 measurements. One tyre was within a smidge of 3mm on every one the other 3.5mm. My take from that was they were correctly inflated for the load.

 

The rear Hankooks which I ran at 65psi, Hankooks recommended for 1900kg, were also evenly worn and had plenty of tread so they are now on the front.