# motorhome tyre pressure ????



## seanb (Jun 21, 2010)

Hi all I have a elnagh marlin 65 motorhome on a 2.8 fiat ducato chassie. Does anyone know the correct tyre pressures for this van . fiat book states 80psi / 5.5bar as does the label on door  this seems alot to me but is it correct ??


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## vwalan (Jun 21, 2010)

could be, experiment 5-10 psi lower and see if you like the ride .then keep your eyes on tread wear. its all trial and error work . cheers alan.


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## lebesset (Jun 21, 2010)

important thing is the maximum axle weights which you use , and the rating of the tyres fitted

if you look on the fiat plate [ under the bonnet ]it will give the axle as well as the vehicle maximum . so post that as well as the load index of the tyre ...at a guess you have 109/107 215/70 15


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## Captain (Jun 21, 2010)

Sounds about right, we have the 2.8 Ducato chassis and run at 5.5 bar.


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## maingate (Jun 21, 2010)

There is only one way to find the correct pressure.

Load up your van to a typical trvelling condition ie: Fuel, water, passengers and general kit, then go on a weighbridge to check the axle weights. You will get a printed ticket with the values on.

Go to tyresafe.org/data/files/motorhome%2008.pdf

You can work out the pressure for your size of tyre from that.


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## John H (Jun 21, 2010)

Captain said:


> Sounds about right, we have the 2.8 Ducato chassis and run at 5.5 bar.



Ditto - 3,500 kg, 2.8 Ducato chassis and tyres at 5.5 bar


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## maingate (Jun 21, 2010)

Running at 5.5 bar means you are very close to the maximum rated pressure for your tyres. In fact it exceeds the max. for some brands.

I had the same problem a few years ago and found it very difficult to get the correct pressure. As it happened, there was a weighbridge where I was working. When I got the axle weights, I phoned up Michelin who gave me the correct information. I had been running at more than 20 psi too much. The difference in handling and the smoother ride were very different afterwards.

I believe that the tyre companies have stopped handing out this info. but it is worth a try.

If you do not know your axle loading then you have no idea if you are overloaded on one or both axles. As VOSA are pulling over m/homes on a regular basis, you are liable for a fine or worse. They are keen to pull m/homes over because of the ones they have stopped, a good percentage were overloaded.


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## lebesset (Jun 21, 2010)

maingate is 100% correct 

tyres should be run at the correct pressure for the load they carry

so first you ascertain the load , then you set the tyre pressure according to the recommendations of the ETRTO 

at a guess we are talking of 215R70 15 109/107 load index here 
this tyre is capable of carrying 1030Kg in single formation , 2060Kg per axle 
if you are running your 3,500Kg vehicle at 2,060Kg per axle 5.5 bar is the correct pressure on rear driven axles , 4.75 bar otherwise ; I trust you are not running at these weights !

I run my vehicle on this size tyre at 1500Kg front axle , and 1900Kg rear axle , and for this I use 4.5 bar and 5.0 bar respectively , apparently high on the front because I prefer this on driven wheels , and a little extra on the rear in case I make an error in loading 

unfortunately a large percentage of motorhomes in europe are overloaded , and consequently there have been failures which people blamed on the tyre manufacturers ; there now seems to be an undisclosed agreement between the manufacturers that for a motorhome they will always quote the maximum pressure of which the tyre is capable and this protects their commercial interests ; at the same time the ETRTO have withdrawn their load/pressure charts , a copyright document , from the public domain ; they also try to persuade vehicle manufacturers to fit larger tyres than are needed , in case of excess [ and illegal ] loading 

however here is a link giving the information you need

http://www.motorcaravanning.com/tyresafe_mh_tyres_08.pdf

there is a member on this forum who was involved in a fatal accident , fortunately he was not to blame and his vehicle was found to be correct in all respects when examined

if you do not know your axle weights how can you be sure you are in the same position ; excessive tyre pressures are dangerous just like low pressures


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## seanb (Jun 21, 2010)

hi on the plate under bonnet it has   3200               kg
                                                 5200               kg
                                             1  1690  kg
                                             2  1750  kg
 on the tyre it has 215 / 70 R  15 C    109 - 107  Q


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## maingate (Jun 21, 2010)

BTW If you are involved in an accident and the Insurance company assessor finds that your tyre pressures are set wrong then your insurance can be null and void. That can be an expensive lesson.

As for manufacturers recommendation, when I had the Elddis Autoquest 120 the problem I had was this:

On the door post the pressure was given as 80 psi. At that pressure the handling was atrocious and my teeth rattled when I hit a pothole. Plus all the crockery etc made such a noise that it got on my nerves.

On the Elddis website, it said 43 psi. At that pressure, the tyre looked almost flat and the handling was even worse. The moral of the story is: TAKE NO NOTICE OF ANY STICKERS REGARDING TYRE PRESSURE.

The recommended pressure (by Michelin) was 55 psi at an axle loading of 1600 Kg per axle.


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## lebesset (Jun 21, 2010)

fine , you have plenty of tyre for the maximum weight 
question is , what load are you actually carrying 

you should load up and go and weigh up  , say half a tank of diesel and half a tank of water , all passengers [ or at least adjust for their weight after !]

presuming you are not much over those weights I would try 4.0 bar front , 4.5 rear , ample until you find out exactly what you are carrying 

you now have the official figures and can ensure that you conform to the tyre manufacturers figures [ doesn't matter which manufacturer , all conform to ETRTO loads ]

incidentally , if you find you have weight problems , it is possible that you can get it uprated a little , with a new plate ; later models had a higher rating on the same chassis if I remember correctly


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## maingate (Jun 21, 2010)

seanb said:


> hi on the plate under bonnet it has   3200               kg
> 5200               kg
> 1  1690  kg
> 2  1750  kg
> on the tyre it has 215 / 70 R  15 C    109 - 107  Q


If you are not sure what the figures mean, then I should explain.

1690 Kg is the max loading allowed on the front axle
1750 Kg "    "    "       "          "       "    "   rear axle

3200 Kg is the MIRO (mass in running order)

5200 Kg is the maximum permissable train weight (weight of van + weight of trailer)

If you add 1 and 2 together, you get 3440 Kg. Subtract the MIRO (3200 Kg) and you get 240 KG left. That is what you can carry in the van. That figure includes passengers and goods and may not necessarily be very accurate. That is why so many vans are overloaded. The manufacturers and especially the dealers often tell porkies when asked about the carrying capacity of a vehicle.


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## Kontiki (Jun 21, 2010)

I have in the past contacted Michelin technical department & they were helpful in telling me what pressures I should be running based on the axle weights.


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## lebesset (Jun 21, 2010)

maingate , am afraid that is not correct 

3200 is the maximum weight of the vehicle fully loaded , what it weighs empty taken away from this tells you the load you can carry 

the reason the total weight allowable on the 2 axles exceeds the total allowed for the vehicle is to allow some flexibility in loading


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## vwalan (Jun 21, 2010)

if we stop now i can say lebesets last statement is correct. i have been in a fatal accident where the other driver was killed .i was exsonerated at the inquest for trying to mount a grass bank to get out of the way . it did mess my head for awhile as the press always blame truck drivers .get your tyres something like it dont overload . if you had heard the inspection that was done on the vehicles you may be amazed .you need the right tyres at about the right pressure .yes ask the manufacturer if you can i worked for michelin for awhile they will always get back to you . i just say play around the pressures arent quite a fixed figure they do vary depending on wether its a truck or carrying passengers. as comfort does play apart in it.


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## maingate (Jun 21, 2010)

Hi Lebesset,

I stand corrected.

The problem with this is that not all manufacturers apply the same criteria when giving maximum weight.

Some use a full water tank, 75% full fuel tank and include the weight of the driver (approximately). Others do it slightly differently.

There have been a lot of complaints from m/home owners on websites that they have been shocked at the weight of their van when they have weighed it. It is not surprising that they have had the weight upgraded. Many have had little choice, otherwise they will be breaking the law.


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## vwalan (Jun 22, 2010)

its a shame that the weight as been brought down with licence laws i always thought merc got it right with the 508. just about right for a camper 5ton. 
if you want max weight it as to be with full tanks and every thing else .then have 200kg spare as every thing you buy or extra pdeople will soon mount up. 3.5 is not enough really. vosa know its easy so makes a good target.
cheers alan.


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## lebesset (Jun 22, 2010)

for me alan is correct in principle...but wrong in the detail

when the 3.5 tonne law was introduced the vehicles were much less sophisticated than they are today  , no power brakes , no power steering etc ; plenty of vehicle for anyone to handle on a car licence; now a 3.5 tonner is like driving a car , little physical effort required

but what has happened is that our motorhomes have changed , much more equipment , much more weight , even bigger people ; whereas once a 3.5  motorhome would carry a tonne of load , now you would be lucky to get half of that 

so I don't see the problem as a decrease in weight to 3.5 , rather a lack of an increase to reflect modern vehicle technology ; the vehicles that most of use drive today are actually designed to run at 4 tonnes or so , all that is needed is to increase all the regulations to that ; there is no reason why not ...vehicles would remain the same overall dimensions , and don't tell me that a bridge that is marked to carry 3.5 won't carry 4.0 , they are actually marked that way to fit the legislation , and for motorway tolls etc they would be carrying the same vehicles 

it will come  too late for me , but as always it will need political pressure ; where is the political pressure in the uk ?..there are beginnings in france and germany I understand 

note however that the new government is going to ignore all current petitions to number 10 ; those petitions were sent ,not because of who the government in power was , but because they were issues that people thought needed addressing ...if this is an indication of the attitude of our new masters , heaven help us ; listen to the people ? not this lot either

a lot of work to change everything ? not at all , just a quick EU law saying that all signs, licences etc currently designated 3.5 are henceforth  legally able to be used by 4.0 vehicles ; then change all the signs , paperwork etc when they came up for renewal ..if that took 20 years , what would it matter ?


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## vwalan (Jun 22, 2010)

the 3,500kg limit only came in in uk 1997 vehicles havent changed that much. germany changed at the same time as us .they could drive up to 7,500kg on a car licence before then. yes france was different and some others were but that didnt effect us. i still say 5ton is ideal for a camper. specially if long terming.
i like mine could be 9.6ton if i voluntary lift the train back up. 
i voluntary down it so pre 97 lic holders can drive it. 
its possible with mine to lower the gvw to 3,500kg and still keep the train of 9,600kg and be driven on a b+e car licence. 
laws and rules all confused yet?
cheers alan.


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## lebesset (Jun 22, 2010)

the only difference is that when you pass your driving test you no longer get a C licence in the uk [ since '97 as you say ]

what constitutes the various categories has remained unchanged since , if I remember correctly the late 1960's ; I remember being given a 16 tonne licence on grandfather rights when these categories were introduced 

in france the 7.5 tonne licence was withdrawn in early 1975 , and reduced to the 3.5 tonne unless you passed a hgv test

my point is that the ..no vehicles over 3.5 in this town , or over this bridge , extra tolls , lower speed limits  etc has existed for many years , and in my view is outdated in the light of improvements in vehicle technology ; this has nothing to do with driving licences as it applies no matter what heavy licence you hold ; the licence , of course , needs updating so that it covers the vehicle up rating , but is not the raison d'etre


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## maingate (Jun 22, 2010)

I agree with much of what has been said on here.

For the last few years, it has become increasingly difficult to get a sub 6 metre coachbuilt or van conversion. The range of choice has disappeared.

With increased size has come less payload due to the 1997 driving licence changes. If the price of diesel rises as much as the merchants of doom are predicting, I think we will see the return of smaller, fuel efficient vehicles.

So hang on to your old VW`s.


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## vwalan (Jun 22, 2010)

regards pressure ,s mine uses 215/75r/16c tyres at 5.25 bar..but the rating is 116/114 so i can have 2500kg on front axle 4500kg on rear axle. when you get tyres always make sure of the weight rating . this also effects the pressures as well.


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## lebesset (Jun 22, 2010)

that's good advice alan 
this camping tyre business may be a scam , but the load index is most certainly NOT
in a number of these sizes there is more than one load index available 
better be sure you get the correct one!!!


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## seanb (Jun 24, 2010)

*thanks to all*

Would like to thank all of you for your advise it is much appreciated .It seems that   check weight , adjust tyre pressure accordingly , give some leeway would be the general consensus so will be visiting local weighbridge with full load and will take it from there cheers all


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## Deleted member 207 (Jun 24, 2010)

There are a few things to look at with tyres - not just pressures.

Most vehicles will have a couple of size options for tyres that can be fitted on the rims as supplied - usually that is a variation of upto 10% (at the maximumu) of the tyre diameter and then the aspect ratio (tyre width to sidewall tyre height). The smaller the aspect ratio (eg 205/75-R15 the 75 is 75% of the tyre width) generally the harder the ride will be as the tyre will not flex as much - but handling will be greatly improved as the tyre will not tend to flex sideways. We run 100% aspect ratio tyres which do a good job on lots of dirt roads, but ain't so hot on nice smooth bitumen.

As all things vehicle its always a compromise - tyre tall = worse handling, tyre short = harsher ride.

Sometimes you can fork out and buy new rims and get tyres to suit a softer ride. 

Generally the light truck tyre business is not about comfort but longevity of tyres.


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