# any suggestions for tyre pressures



## The-Cookies

Hi, Renault master base vehicle 3500kg max with michelin 225/65/16 cp tyres

michelin say 62 front 80 rear ( tyres have max 80 psi on them )
hand book says 72 front 72 rear
looking on web sites i get different again.


any one with similar set up to ours got any other ideas or is it just trial and error.


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## blackbirdbiker

The-Cookies said:


> Hi, Renault master base vehicle 3500kg max with michelin 225/65/16 cp tyres
> 
> michelin say 62 front 80 rear ( tyres have max 80 psi on them )
> hand book says 72 front 72 rear
> looking on web sites i get different again.
> 
> any one with similar set up to ours got any other ideas or is it just trial and error.


Running at those pressures is going to make a very hard ride 8O I've set mine at 55 front and 60 rear or 65 with the scooter on.

It's a suck it and see job really, just by looking at the tyres as the van is on a smooth surface they should have a very small but visable bulge at the bottom.
Hope this helps,

Keith.


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## cabby

The correct answer for you is, take it fully loaded to the weighbridge, weigh front axle and then full vehicle.
contact Michellin on the number quoted on another post and they will tell you the best pressure, this is a service they do for their customers.  

cabby
edit. try this number 08453 661 535


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## wakk44

cabby said:


> The correct answer for you is, take it fully loaded to the weighbridge, weigh front axle and then full vehicle.
> contact Michellin on the number quoted on another post and they will tell you the best pressure, this is a service they do for their customers.
> 
> cabby


Spot on,excellent advice,thanks Cabby 

I got my axle weights from the MOT certificate and then contacted Continental(I have Conti Vancos fitted)then they e-mailed me the recommended tyre pressures straight away.


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## andrewball1000

cabby said:


> The correct answer for you is, take it fully loaded to the weighbridge, weigh front axle and then full vehicle.
> contact Michellin on the number quoted on another post and they will tell you the best pressure, this is a service they do for their customers.
> 
> cabby
> edit. try this number 08453 661 535


Hi, I did exactly this last year as my Renault handbook gave one set of pressures and the Knaus handbook another. Michelin then gave me their recommendation for the front tyres but would not commit on anything less than 80 for the rear. I got the impression that they felt this was too high but would not go against a handbook in case they became liable.

Andrew


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## The-Cookies

what Andrewball1000 says is the impression that i got from michelin tyre maximum 80psi, so they say 80psi, covers themselves upto that pressure as most weight is at the back . not really an informative answer from them


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## 5bells

We have a similar set up Renault Master 3,5 tonne chassis Burstner Delphin.
Burstner hand book says 4.5 bars front 5.5 bars rear, this is about 66 psi front to 80psi rear. This was too hard a ride for us so we find 70 rear and 60 front to be I believe a good balance.
This is without tow hook and not overloading rear locker.
It is tempting to go lower for an even softer ride but imho I believe this can contribute to degradation of the tyre walls on these fairly
rigid camper tyres.
I will try the Michelin site though after checking my last weighbridge ticket.
Regards Ray


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## grizzlyj

Hi

For my huge big off road tyres the recomendation from others with the same set up is;

On the sidewall it tells you the maximum load (kg) at a maximum pressure (psi). 

Divide that load by that pressure and it gives you a figure of kg per psi.

Having weighed each axle of your loaded camper you know the axle weight, half that gives you load per tyre.

That tyre load multipied by your kg/psi figure gives you the pressure to use.

Personally, from that I've added a bit at the front for comfort, and add a further 5psi for high speed runs. This gives a footprint size that you would expect, and is well within the maximum pressure allowed (since I'm well within the max weight you would expect that! ). 


Of course this may well go against what your handbook may say for your vehicle, and the pressures you run are your choice. 

But when people have in the past quoted their tyre maximums and weights, a calculation for their situation out of my curiosity seems to back up the method I'm using.

Jason


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## BrianJP

As mentioned in previous posts on the subject look at this PDF.

http://www.tyresafe.org/data/files/motorhome leaflet.pdf

I also E mailed Continental tyres tech help with axle and gross weights and they gave me the pressures within 30 min.
My motorhome came from a dealer with the pressures at 80psi ( as in Fiat handbook)front and rear,when in fact Continental say 58 front and 65 rear when max loaded.I wondered why it bounced down the A1 on the way home !


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## andrewball1000

grizzlyj said:


> Hi
> 
> On the sidewall it tells you the maximum load (kg) at a maximum pressure (psi).
> 
> Divide that load by that pressure and it gives you a figure of kg per psi.
> 
> Having weighed each axle of your loaded camper you know the axle weight, half that gives you load per tyre.
> 
> That tyre load multipied by your kg/psi figure gives you the pressure to use.
> 
> Personally, from that I've added a bit at the front for comfort, and add a further 5psi for high speed runs. This gives a footprint size that you would expect, and is well within the maximum pressure allowed (since I'm well within the max weight you would expect that! ).
> 
> Of course this may well go against what your handbook may say for your vehicle, and the pressures you run are your choice.
> 
> But when people have in the past quoted their tyre maximums and weights, a calculation for their situation out of my curiosity seems to back up the method I'm using.
> 
> Jason


Jason that is a really helpful calculation. Having the same set up as The Cookies I wanted to give some more detailed data than my first posting so have checked my tyres this morning and used your formula.

My tyres are Micheline 225/65 R16CP rated at 1120kg @ 80psi
The Renault Master handbook gives 65psi front and 80psi rear
The Knaus Handbook gives 55psi front and 63psi rear

After contacting Micheline last year I weighed both axles with the van fully loaded with water, fuel and gas etc etc with me in it
Front axle was 1540kg and rear 1860kg

On this info Micheline recommended 52psi front and 80 rear. (see previous post)

Not knowing better I used the van all last year on the continent on all back roads using and in between estimate of about 58psi on the front and 70psi on the rear. Mpg has never been lower than 28mpg.

Now using Jason formula calculation of half axle weights 770/1120x80 = 55 front & 930/1120x80= 66 rear. If you use the add ons he suggests then it is the same as I have been using.

Thanks Jason


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## grizzlyj

andrewball1000 said:


> grizzlyj said:
> 
> 
> 
> Hi
> 
> On the sidewall it tells you the maximum load (kg) at a maximum pressure (psi).
> 
> Divide that load by that pressure and it gives you a figure of kg per psi.
> 
> Having weighed each axle of your loaded camper you know the axle weight, half that gives you load per tyre.
> 
> That tyre load multipied by your kg/psi figure gives you the pressure to use.
> 
> Personally, from that I've added a bit at the front for comfort, and add a further 5psi for high speed runs. This gives a footprint size that you would expect, and is well within the maximum pressure allowed (since I'm well within the max weight you would expect that! ).
> 
> Of course this may well go against what your handbook may say for your vehicle, and the pressures you run are your choice.
> 
> But when people have in the past quoted their tyre maximums and weights, a calculation for their situation out of my curiosity seems to back up the method I'm using.
> 
> Jason
> 
> 
> 
> 
> 
> Jason that is a really helpful calculation. Having the same set up as The Cookies I wanted to give some more detailed data than my first posting so have checked my tyres this morning and used your formula.
> 
> My tyres are Micheline 225/65 R16CP rated at 1120kg @ 80psi
> The Renault Master handbook gives 65psi front and 80psi rear
> The Knaus Handbook gives 55psi front and 63psi rear
> 
> After contacting Micheline last year I weighed both axles with the van fully loaded with water, fuel and gas etc etc with me in it
> Front axle was 1540kg and rear 1860kg
> 
> On this info Micheline recommended 52psi front and 80 rear. (see previous post)
> 
> Not knowing better I used the van all last year on the continent on all back roads using and in between estimate of about 58psi on the front and 70psi on the rear. Mpg has never been lower than 28mpg.
> 
> Now using Jason formula calculation of half axle weights 770/1120x80 = 55 front & 930/1120x80= 66 rear. If you use the add ons he suggests then it is the same as I have been using.
> 
> Thanks Jason
Click to expand...

Thanks for checking that out!

Mine are 395/85R20 XZLs and Michelin UK don't even list them. I think that info initially came from Michelin USA who seem to be a lot more forthcoming, but what works for tyres taking nearly 6 tons each and more normal camper tyres may not be the same! Its nice to know that in your case at least it seems to!

Cheers

Jason


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## BrianJP

Just to add a bit of confusion to this thread.As the Jason formula ,whilst logical did not give figures for me similar to those indicated on the tyresafety.org doc or the figures given to me by Continental I looked into it further.It seems the Michelin tyres that are currently on my van have a load rating (109) 1030kg at 80psi whereas the spare fitted with a brand new (2010 year)Continental Vanco Camper is rated at 1030kg at 69psi.When the Jason formula is applied to these figures it comes closer but still not the same as those given to me by Continental so I think some other factor must be included in calculating these pressures,other than just the tyre load rating and max pressure.It also seems that different manufacture tyres may require different pressure tables Now i'm really confused?


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## grizzlyj

It would be nice to think that all there is to it is a given psi for any given load for that tyre. How much research can any manufacturer do into every specific fitment? A simple guideline has a lot going for it.

But as has been said there may well be more to it regarding hitting an object at speed for instance.

There has I believe been some legal interest in overloaded motorhomes in the USA and Oz, perhaps the likes of Michelin are more wary when quoting for that usage considering the seemingly quite high numbers who are overloaded?

Jason


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## andrewball1000

BrianJP said:


> Just to add a bit of confusion to this thread.As the Jason formula ,whilst logical did not give figures for me similar to those indicated on the tyresafety.org doc .....


I did look at the Tyresafety sheet last year but the nearest to my axle weight was 58psi at 1952kg. If you extrapolate these down to 1540kg front and 1860kg rear ( I dont know on what basis) you get much lower figures than I would be happy to run at . Jasons formula is the first logical information I have come across in a year that gives a sensible figure between all those I was quoted (see last post) and for the first time I am less confused.

Andrew


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## BrianJP

I have just sent an Email to the guys at Continental to ask them what criteria they use to calculate the pressures and if there is a simple formula that can be applied by anyone.They are noramlly very responsive so will post their reply here when I get it.


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## The-Cookies

here's the bit i don't get, we had a twin wheel caravan , tyres where this specific make and size this is the pressures you need , why can't motorhomes have the same easy to apply rules. and what if i do experiment with the pressures and i was unfortunate to have an accident and anyone examining the crash decided i had the wrong pressures in and was responsible.


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## Chudders

About 18 months ago I asked Michelin for their recommended tyre pressures. I supplied them with front and rear axle weights after visiting a weighbridge. They e mailed me a reply which gave suitable pressures for the front including as they said an allowance for weight transfer under braking and cornering. The rear if I recall they gave pressures of 65 PSI.
However on contacting them again a few months later I was informed that they had discussions and it was generally felt that motorhomes run at their maximum if not over maximum load. They had changed their policy. They will give figures relating to a front axle having regard to the axle weight but now specify 80 PSI for the rear regardless of the axle weight given. At that time I think the tyres were Michelin Camping 215/75 R 16.
I have since changed motorhomes and have a TAG axle and with this configuration they will give pressures for the rear dependant on axle weights.
All very confusing (and a hard ride)


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## BrianJP

BrianJP said:


> I have just sent an Email to the guys at Continental to ask them what criteria they use to calculate the pressures and if there is a simple formula that can be applied by anyone.They are noramlly very responsive so will post their reply here when I get it.


Just got reply from Conti as follows;

There isnt' a formula as such. However, there is almost a sliding scale
based on weight increments from the minimum to the maximum loadings.
However, these are dependent on individual sizes and service descriptions.

This information can be found in our technical data book. I have attached a
PDF copy for your persual. You can find the details for camper/van tyres on
page 88.

(See attached file: Conti_Tech_data_book_2010-11_en.pdf)

Regards

Craig Sterry

The Data book tells you just about everything you wanted to know about tyres including tables with pressures for all tyres including van and camper tyres for specific axle weights.However it is a pdf of over 2mb so I cannot attach it to this post . If the administrators want it to put on the forum I can Email it to them.


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## nicholsong

About a year ago I contacted Michelin re my tyre pressures.

They gave a vague answer, which to my mind was written by a lawyer

I then contacted VOSA on the assumption that if they did a roadside inspection and that, having weighed the vehicle they would have the information in order to assess whether the tyres were correctly inflated.

VOSA just referred me to the manufacturer, despite my having explained that Michelin, unlike it appears Conti, will not give specific answers.

So if VOSA wish to allege tyres are not at the right pressure it would be worth challenging them to provide the data to prove it.

Geoff


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## BrianJP

Interestingly the Chart in the Continental data book is almost identical to the one produced by tyresafety 
http://www.tyresafe.org/data/files/motorhome leaflet.pdf

so I guess the figures here can be relied upon?


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## papaken

*tyre pressures*

just collected my first motorhome and also have a query with tyre pressures, I have two MATADOR MAXILLA 215/R15C's on the front and one on the rear along with a MITCHELIN XC CAMPING 215/70R 15C any Autocruise Starspirit owners out there that can help???


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## BrianJP

As stated many times before.Take vehicle to weighbridge either fully loaded with passengers as if going on a trip or with full fuel & water tanks and get it weighed . Then look at this chart, its fairly accurate and supported by most tyre manufacturers although Continental advise slightly higher pressures in rear tyres because of weight shift when cornering.
http://www.tyresafe.org/data/files/motorhome leaflet.pdf

If you only had it weighed with full tanks etc you will now know what payload you can carry and adjust tyres as necessary from the chart.A good starting point though is to use pressures indicated for the max front and rear axle weights which maybe a little higher than needed in practice but will be safer than underinflating. I did this until I got to a weighbridge


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## papaken

*rear tyre mix a problem?*

My thoughts are do i have the same pressure in the rear tyres as the Michelin says 80 psi or is this to hard? Must i drop the Michelin pressure to keep both rear tyres the same? not used to dealing with mixed tyres.


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## camallison

*Re: tyre pressures*



papaken said:


> just collected my first motorhome and also have a query with tyre pressures, I have two MATADOR MAXILLA 215/R15C's on the front and one on the rear along with a MITCHELIN XC CAMPING 215/70R 15C any Autocruise Starspirit owners out there that can help???


Matador are part of the Conti group I think - they gave me figures by return email last year.

Colin


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## camallison

*Re: tyre pressures*



camallison said:


> papaken said:
> 
> 
> 
> just collected my first motorhome and also have a query with tyre pressures, I have two MATADOR MAXILLA 215/R15C's on the front and one on the rear along with a MITCHELIN XC CAMPING 215/70R 15C any Autocruise Starspirit owners out there that can help???
> 
> 
> 
> Matador are part of the Conti group I think - they gave me figures by return email last year.
> 
> Colin
Click to expand...

I have sent you a PM

Colin


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## BrianJP

*Re: rear tyre mix a problem?*



papaken said:


> My thoughts are do i have the same pressure in the rear tyres as the Michelin says 80 psi or is this to hard? Must i drop the Michelin pressure to keep both rear tyres the same? not used to dealing with mixed tyres.


Firstly Its not ideal mixing two different tyres on same axle although in practice vehicles often end up with this.However as Iam not sure ,is the Matador is a specific motorhome tyre ? as if not it wont be the same construction as the Michelin XC and there could be an issue there.Personally I would have wanted to start off with 4 new tyres all the same.If it is a non motorhome tyre then the inflation pressure will be lower than for a motorhome tyre for any given load.
This is obviously not ideal, and I am suprised that a tyre fitter would do this as the tyre characterisics will be different.
I am sure though that are many owners out there with all kinds of tyres mixed on their vehicles.
Regarding pressure ,if you are reading the Michelin figure of 80psi from the sidewall then this is the max pressure for the tyre.( Although the Fiat Ducato manual for example quotes pressures of 80psi front and rear for motorhomes which is rediculously high).
In my case the vehicle has a maxweight of 3400kg and the pressures for max axle weights from the Tyres safety table for motorhome tyres are 58 front and 65 rear , although continental recommend 73rear as I said previously because of weight shift on the vehicle rear end.
Of course your camper will be different depending on axle weights which is why a vist to weighbridge is recommended.
Hope this is of some help. I was faced with a similar situation recently when I bought a motorhome and having no info on pressures from the manufacturer ,only what it said in the Fiat base vehicle manual I read lots of posts here and contacted Continental who are very helpful and also used the tyre safety chart 
to arrive at a good working pressure for my vehicle.


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## papaken

*tyre mix*

going through all your suggestions and after a visit to a weighbridge will finally sort them out, just checked and the spare isa michelin so maybe i will put that with the other on the rear, will post my eventual results.


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## BrianJP

*Re: tyre mix*



papaken said:


> going through all your suggestions and after a visit to a weighbridge will finally sort them out, just checked and the spare isa michelin so maybe i will put that with the other on the rear, will post my eventual results.


Thats what I would do however check manufacturing dates on the Michelins.Tyre age and condition of tyrewalls is far more important than tread level.


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## bungy69

So...i thought...Hmm ill go have a look at mine

So, all 4 tyres are Conti 215/70 R15 CP with a max load rating of 1030kg @69psi but there is some small writing just by the rim which basically says, as Motorhomes are special things they can be inflated above the maximum stated to 5.5 bar (79.7 psi)

now mine has a max MTPLM of 3500Kg (very common i guess) so no issues there, but why state a max and then state an even higher one in small writing (always read the small print eh?) for MH's???


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## BrianJP

bungy69 said:


> So...i thought...Hmm ill go have a look at mine
> 
> So, all 4 tyres are Conti 215/70 R15 CP with a max load rating of 1030kg @69psi but there is some small writing just by the rim which basically says, as Motorhomes are special things they can be inflated above the maximum stated to 5.5 bar (79.7 psi)
> 
> now mine has a max MTPLM of 3500Kg (very common i guess) so no issues there, but why state a max and then state an even higher one in small writing (always read the small print eh?) for MH's???


\these are 2 different issues.The tyre itself has a max loading index 109 that equates to 1030kg at 80psi.
Your vehicle has max weight of 3500kg and assuming you attain that weight it is distributed between front and rear axles which have an individual max weight,that should be indicated on the vehicle weight plate. Therefore the only answer as stated before by myself and many others is to go t a weighbridge either fully loaded for a trip or with tanks etc full plus personel and calculated pressures from there using tables to be as staed previously.


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## bungy69

BrianJp - i appreciate what you say and i do understand it and have done all of this in the past, including the weighing...but

loading index of 109 equates to an absolute maximum of 2060kg at 69 psi for my particular tyre (recommended is 1854 at 60psi), according to the tyresafe chart that is

But the tyre states 2 different maximums, one which says maximum for single of 1030kg at 69 PSi (which is substantially lower than the tyresafe pdf) and very small writing that says you can actually go to 79.7psi for motorhomes (and i assume it means the max weight can then go upto 1189.7kg - using the previous maths - and again different from the pdf), the later being specially for motorhomes - but this is a motorhome tyre, so why the difference!?!

Whilst this isnt an issue for the weight its carrying, my point is

the tyre states two different maximum possibilities, the pdf shows different values, the info from tyre techies are different again

But where someone doesn't know...who do they believe? does it matter?

but like i said not a real problem until you get upto the 4700kg upwards bracket in terms of load capability on my particular tyre, but getting the psi right for each M/H weight once the weighbridge etc has been done can be tricky - based on the conflicting information

Not trying to make an argument here BTW or criticise peoples advice and knowledge - just an observation


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## BrianJP

Firstly I am no expert just someone perhaps like yourself who wants to get their tyre pressures correct.So having read lots of posts here on the subject with all kinds of opinions and theories I decided to try and get definitive data on the subject.
I had numerous Email exchanges with the tech guys at Continental who are very good and informative.
So without wishing to confuse things further tyres with load index 109 have a max load capacity of 1030 the pressure at which they acheive this depends on the tyre manufacturer and also the tyre position on the vehicle. For example Michelin just state 1030 kg at 80psi whereas Continental state 1030kg at 69psi and on the tyre it has printed max pressure 5.5bar ( 80psi).
But this doesnt mean that you can increase the load on the tyre if you inflate to 80psi.It just means that the tyre can be inflated to 80psi if required. If you look at the tyresafe chart for 109 index tyres you can see that for rear axle driven wheels 80 psi is required for 2060 kg ( 2x1030). In fact Continental recommend 80psi for max load of 1030kg (and a sliding scale for lesser weights) for rear tyres regardless of whether they are driven or not.Their explanation for this is because in Motorhomes where most of the weight is on the rear axle there can be a weight shift under cornering that requires higher pressures ,whatever that really means?
My advice to anyone is to check the axle weights and then ask the tyre manufacturer for the correct pressures as the Tyresafe chart although in general supported by most manufacturers is only a guide.
Anyway Conti did send me a PDF of their latest tyre data handbook that covers more or less anything you want to know about tyes for all types of vehicles with tables for everything including pressures.It is obviously focussed on Continental tyres and their applications.It is to large a file size to upload here but if anyone wants it I can Email it to them.


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## bungy69

Thanks for that brianJP

Especially the 80psi bit - going to give that a try on the rear!! 

ive been contemplating that for a while - hard ride verses more serene but with increased 'risk' with weight shift in certain circumumstances ..gave up trying to work it out - gawd knows why i was even trying to be honest!

a few months ago, i borrowed a friends caravan scales, out of curiosity to see the variance in weight across an axle, the amount of change was ridiculous, as in, shift a bit of weight in side like a box of tinned food, and the difference across the axle was sometimes 4-5 times more than the weight of the tins - i gave up 

so i settled on using what was recommended on the tyres and left it at that (front was a bit lower as the steering ended up being way to light and 'bouncy')


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## papaken

to add to the saga i have checked the only sticker info (in french) i can find on the wheel arch of my drivers door and one shows a sketch with all 4 pressures 79.5 +1, the other sticker has a table 
with titles psi(bar) kg psi(bar) and some french descriptions.
In the first box under psi is 80 under kg are 620,900and 1460 and along side under psi are 13+/- 4,33+/-4,80 -4 respectively.(clear as mud but could not tabulate it properly). 

Unfortunately i cannot read the french :lol: 
I cannot find a weight plate!and am awaiting my reg doc from DVLA.


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## The-Cookies

bearing in mind that tyre pressures are 1 of the most important things that have to be checked on a vehicle, is it not time that motorhome manufacturers got this issue sorted out.


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## papaken

*plate details*

found a plate under the bonnet only gives numbers:
3300kg,
5300,
1-1750,
2-1850.on the bottom AX and below that 1.20 whatever they mean??


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## pete4x4

Using the info supplied by Brian , thank you, it's interesting to see that the recommended pressures for my max weight are lower than those in the door, for my weighbridge weight i need to run at 3.0 bar Front and 4.5 rear. The door plate is 5.5 Front and rear, should really be for max weight 4 front 4.5 rear big difference


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## 5bells

I beleive no one has metioned on this thread yet the difference jn "camper" and regular tyres.

The reason I mentioned this in my earler reply was because I have read somewhere on mhf about premature cracking of the side walls on these camper tyres especially the michelins.

We have these on our van four years old now as per date on tyre 17000 mls and no sign at all so far of any cracking.

Although the tyre safe recommends a lower pressure than the 70psi rear 60psi front I use I am wary of using too low a pressure as much of the loading IMHO I believe is then taken up by the very stiff sidewalls of these tyres which makes the walls flex more than they were intended too. 

This is only an opinion not very scientific I know but it would be interesting to know if anyone with these tyres on lower pressures have had any deterioration of the sidewalls.


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## pete4x4

Simple test for that is after a journey feel the sidewall if its hot then pressure is too low, warm is ok cold is probably over inflated. 
Crude but effective


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## duxdeluxe

Late reply to this but I put the van across a weighbridge today to obtain the axle weights then using Grizzlj's calculations on post 8 of this thread. Calculated at 52 psi and 65 psi front and rear. Emailed Michelin who replied very quickly with 52psi front and the maximum 80psi rear to allow for loading. So based on other tyre pressure discussions I decided to follow Michelin recommendation for the front but as the rear axle is much lighter than the max even fully loaded to go for proportionally lower pressures at the back. Better than 80 all round.....


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## nicholsong

Interesting that you got a specific reply from Michelin.

From other threads many of us could not get specifics from them even when we gave actual axle weights.

Maybe they have changed policy.

I have now dumped their tyres - too much side-wall cracking even on camper tyres.

Geoff


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## FoweyBoy

I have just fitted Michelin Agilis Camping (215/70 R15CP 109Q) to replace my old (2004) Michelin Camping tyres.

My axle loadings (fully loaded on weighbridge) are Front 1500kg, Rear 1900kg (rounded up weights). My plated maximum weights are 3400/1750/1900kg, so I am operating at the maximum rear axle loading (like most people?).

I recently emailed Michelin with my axle loadings and got advice of Front 1500kg = 50psi, Rear 1900kg = 80psi.

On the Tyresafe table 
(http://www.tyresafe.org/tyre-safety/tyre-safety-information/240-tyre-safety-information-motor-homes) 
for my tyre specification
Front at 1795kg (minimum they give) = 58psi [so less than 58psi for 1500kg.]
Rear 1885kg = 62psi [say for 1900kg = 63psi).

For my old tyres Michelin some years ago (2007) gave me:-
Front 1420kg = 47psi
Rear 1840kg = 58psi
[I had less gear on board in those days!]

Conclusions:-
1. For old and new tyres on the front the advice from Michelin and Tyresafe are similar i.e. around the 50psi value.

2. For the old tyres on the rear the advice from Michelin in 2007 and Tyresafe now are similar i.e. around the 60psi value.

3. For the new Agilis tyres Michelin have changed their advice and quote 80psi (I believe regardless of the loading (within safe limits)).

80psi seems very high to me, and also to my tyre supplier. I know the label on the cab door post states 80psi, but 80psi will probably give a very hard ride at the back.

The problem is if I reduce the rear pressure below 80psi I am going against the latest Michelin advice and what are the legal and insurance implications :?:


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## nicholsong

Methinks Michelin are giving advice from their legal dept. not their engineers/designers -or their sales dept - tyres run at too high a pressure will wear unevenly across the tread and need replacing sooner.

I ignored Michelin advice. I followed Tyresafe and a few others.

Go down a few psi - after a few miles check the temperature - if the psi it is too low for the weight the tyre will be hot (not just warm)

I am still amazed that the only advice from government bodies including VOSA was 'check with the tyre manufacturer' What are they doing in their vehicle testing units?

Geoff


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## Whiskeymac

Is there anyone out there in the police, insurance or legal professions that can state what tyre pressures are checked against in the event of a fatal accident?


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## BillCreer

Hi, 

The Michelin people recently told me that the manufactures had all agreed on the 80 psi on the rear for "safety reasons" on motorhomes.
The front pressure was used to adjust for comfort dependant on the weights given to them.


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## Morphology

Adding this for completeness.

I have Continental Vanco Winter 2 tyres (ie NOT camping tyres), designation 225/65 R16C 110 R on my Knaus Sun Ti.

I emailed my axle weights to Continental, and asked them what tyre pressures I should use. They emailed back saying:

Front Axle @ 1560 kg = 3.25 bar / 47.1 psi 
Rear Axle @ 1900 kg = 4.00 bar / 58.0 psi 

Morph.


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