Tyre pressure....again. (1 Viewer)

[Camper634]

Just picked up my new van and all is well apart from one thing.The ride seems hard in comparison to my previous van.The handbook suggests 80 psi all round but the dealer has set them to 67 front 71 back.Dies a hard ride mean overinflated tyres?It is a 3.5 ton van on a new fiat Ducati chassis and I would say medium load and 2 passengers.Any help appreciated.

 

[sdc77]

@Ovalball Lots of threads on here re tyre pressures.
Basically weigh front and rear axles and provide manufacturer with tyre details and weights. They will give you correct pressures. If it's fitted with continentals there's a chart posted in resources that might help. (Dealer pressures sound more realistic tbh)

 

[Boringfrog]

Old van, old suspension, new van, new suspension. Give it a while, you might get used to it.

^{_{Subscribers  do not see these advertisements}}

 

[The Nomad]

Just look at the tyres. They should spread a little across their width at the area of contact with the ground. From what I've seen over the years, very many MH owners have their tyres substantially over inflated....no lateral contact spread and even domelike ballooning across the tread face.

 

[KeithChesterfield]

Get thee to a weigh Bridge (about a fiver) and find thy axle weights when fully loaded in holiday mode.

Then return with thy results and all will be revealed to thee.

My Continentals for a similar motorhome to thine are 61psi Rear and 51 psi Front - saves having to use extra adhesive for the false teeth and gives a good ride.

 

[Boringfrog]

Get thee to a weigh Bridge (about a fiver) and find thy axle weights when fully loaded in holiday mode.

Then return with thy results and all will be revealed to thee.

My Continentals for a similar motorhome to thine are 61psi Rear and 51 psi Front - saves having to use extra adhesive for the false teeth and gives a good ride.

Amen....

^{_{Subscribers  do not see these advertisements}}

 

[pops]

I use the same pressures as@ KeithChesterfield. The ride is much better than the original pressures.

 

[138go]

Wait till it's loaded then you will notice a difference. They bounce around all over the place with nothing in. Add a couple of tons of junk and they just glide over the pot holes.

Seriously. Load it up with everything you need. Add the bodies and pets and head down to a weigh bridge. Phone the tyre manufacturer with the weights on each axle and they will tell you the correct pressures.

 

[AndrewL]

The handbook suggests 80 psi all round but the dealer has set them to 67 front 71 back.Dies a hard ride mean overinflated tyres?It is a 3.5 ton van on a new fiat Ducati chassis and I would say medium load and 2 passengers.Any help appreciated.

I have a very similar question (sorry, but it is such a minefield!). At handover the dealer pointed out the pressure sticker on the door post, but they have inflated the tyres to about the same as yours. We have Hankook Vantra LTs on the front and Nankang Passion CW-20s on the rear. I am loath to over-inflate, and unsure what to set on TyrePal.

^{_{Subscribers  do not see these advertisements}}

 

[Camper634]

I have a very similar question (sorry, but it is such a minefield!). At handover the dealer pointed out the pressure sticker on the door post, but they have inflated the tyres to about the same as yours. We have Hankook Vantra LTs on the front and Nankang Passion CW-20s on the rear. I am loath to over-inflate, and unsure what to set on TyrePal.

Yes that's my quandary too.Bought a Fit2go kit and want to make sure the tyres are correctly inflated.

 

[Boringfrog]

At handover the dealer pointed out the pressure sticker on the door post.

Don't you just love them dealers......

 

[pappajohn]

In general, the weights on the data plate are MAXIMUM pressures the tyre is safe at and have no bearing on the required pressures .
My old Kontiki ran at 60psi rear and 50psi front.
No excess tyre wear or high temperature and handling was acceptable.

^{_{Subscribers  do not see these advertisements}}

 

[Deleted member 29692]

Same as always you need to speak to the tyre manufacturers.

Nobody else - not the chassis manufacturer, not the van converter, not the dealer, not anyone on here - can give you the correct pressures.

 

[SandJ]

I can give you some as per photo for various weight

 

[peterc10]

View attachment 157109
I can give you some as per photo for various weight

Trouble is that that is for Continental tyres. Who knows whether other makes are the same construction and strength.

^{_{Subscribers  do not see these advertisements}}

 

[DL42846]

Just picked up my new van and all is well apart from one thing.The ride seems hard in comparison to my previous van.The handbook suggests 80 psi all round but the dealer has set them to 67 front 71 back.Dies a hard ride mean overinflated tyres?It is a 3.5 ton van on a new fiat Ducati chassis and I would say medium load and 2 passengers.Any help appreciated.

I have a Fiat Ducato base Motor home. The hand book and the label inside the door says. 5 bar in the front and 5.5 bar in the rear. That's 72.5 psi front and 79.8 psi in the rear.
Also contacted Michelin and asked there advise. They gave the same pressures but said I could reduce the front to 4.5 bars (65 psi) I tried a short run but the steering felt woolly and a little extra effort was required on the steering. I didn't like it, i went back to the recommended pressures of 5 bar in the front. Comfort wise, I don't feel much difference between 4.5 bars or 5 bar in the front.

 

[SandJ]

Trouble is that that is for Continental tyres. Who knows whether other makes are the same construction and strength.

As I said I can give you some other makes can be contacted

 

[AndrewL]

Same as always you need to speak to the tyre manufacturers.

Nobody else - not the chassis manufacturer, not the van converter, not the dealer, not anyone on here - can give you the correct pressures.

I did try that - but the tyre manufacturer said I should speak to the moho manufacturer!

^{_{Subscribers  do not see these advertisements}}

 

[sdc77]

I did try that - but the tyre manufacturer said I should speak to the moho manufacturer!

Sorry
What tyres do you have??

 

[sdc77]

I have a Fiat Ducato base Motor home. The hand book and the label inside the door says. 5 bar in the front and 5.5 bar in the rear. That's 72.5 psi front and 79.8 psi in the rear.
Also contacted Michelin and asked there advise. They gave the same pressures but said I could reduce the front to 4.5 bars (65 psi) I tried a short run but the steering felt woolly and a little extra effort was required on the steering. I didn't like it, i went back to the recommended pressures of 5 bar in the front. Comfort wise, I don't feel much difference between 4.5 bars or 5 bar in the front.

So when you contacted michelin what axle weights did you give them?
I'm assuming that you didn't weigh the axles so therefore don't have an accurate tyre pressure.
How do you know that the handbook is referring to Michelin tyres btw ..

 

[Deleted member 29692]

I did try that - but the tyre manufacturer said I should speak to the moho manufacturer!

Different makes and models of tyre have different weight and pressure characteristics.

The motorhome converter will not have carried out calcs or tests on every possible tyre you could fit to your motorhome. At the very best they might have done it for whatever they've supplied with the vehicle, maybe not even that, so they could possibly give you the correct pressure for one specific tyre. If you're running different ones, even from the same manufacturer, then chances are those pressures won't be correct.

If a tyre manufacturer has told you that you were either talking to the wrong person or asking the wrong questions.

The fact that it's a motorhome isn't relevant. You need to provide them with all the details of the tyre and accurate individual axle weights for the vehicle and you will get an answer.

^{_{Subscribers  do not see these advertisements}}

 

[funflair]

I have just put this in the other tyre pressure thread but I think it is just as pertinent here, the tyres important characteristics are load rating and maximum pressure so.

If you divide axle loading from weighbridge by maximum allowed from tyre load rating and then multiply this by the maximum tyre pressure you will get a very close approximation.

I often check this when people come back with manufacturer figures and I find it to be accurate, if you want to go a bit over OK but I wouldn't go under.


Martin

 

[DL42846]

So when you contacted michelin what axle weights did you give them?
I'm assuming that you didn't weigh the axles so therefore don't have an accurate tyre pressure.
How do you know that the handbook is referring to Michelin tyres btw ..

I did give them the axle weights. 1440 kg on the front. And 1880 kg on the rear. When I rang Michelin here in Clermont Ferrad ( Head Office) The guy I spoke with first checked on his computer to see what Fiat Ducato recommended pressures were. 5 bar front 5.5 bar rear. I explained to him I had seen all sorts of different recommendations ranging from 3 bar in the front and 4 bar in the rear. He was adamant that for a camper 5.5 bar was the correct pressure for the rear. He suggested the other recommendations my have been for a Fiat Ducato van as in a white workman's van. He said I could try reducing the front down to 4.5, but the recommended pressure was 5 bar. I had also sent off several emails to Michelin earlier but didn't have a reply, I told him I was disappointed that no one had replied. Then after an hour the replies started rolling in.
Personally I'm quiet happy with 5 bar front and 5.5 bar rear. I don't find it uncomfortable and it might just be me, but it feels right. 4.5 bar front felt as if the steering required extra effort and felt woolly. I felt extra strain was being put on the steering joints and Fiats don't seem very reliable or robust at the best of times. Hope the above helps.
Below is one of the replies:

• contact@tc.michelin.eu
  
• 4 Apr at 10:24 AM

To

• Deleted my email address.

Message body
Hello Michael,


Thank you for contacting MICHELIN Customer Service!



First off apologies for the lack of response from our part. I have checked in our systems for any emails received from you and since there aren´t any I suppose that there must have been some sort of technical issue in receiving your messages.



Secondly, the following recommendation is only given if your motorhome is equipped with MICHELIN Agilis Camping with metal valves.



The recommended tyre pressure for the rear axle of a motorhome running on the MICHELIN Agilis Camping is 80 psi. Its reinforced construction and the use of higher pressures is designed to cope with continual heavy loads sometimes found on motorhomes and can help with wear pattern issues if lower pressures are used particularly on the rear axle.
The front tyres however can be adjusted to a pressure of 65 psi for a more comfortable ride and optimum performance.



I hope this information is helpful to you and please don´t hesitate to contact us again if you have anymore questions or concerns. We will be happy to help.


Kind regards,


Vassilena


MICHELIN Customer Service
Tel: 0845 366 1590

 

[DL42846]

I have just put this in the other tyre pressure thread but I think it is just as pertinent here, the tyres important characteristics are load rating and maximum pressure so.

If you divide axle loading from weighbridge by maximum allowed from tyre load rating and then multiply this by the maximum tyre pressure you will get a very close approximation.

I often check this when people come back with manufacturer figures and I find it to be accurate, if you want to go a bit over OK but I wouldn't go under.


Martin

Hi, I have been trying to get my head round the figures you have suggested and I'm having difficulty. It is first thing in the morning here and I have only had one cuppa. According to your calculations what would be your recommended tire pressures based on front axle weight 1440 kg, rear 1880 kg on the Michelin camper tires. I think the max pressures on them are 5.5 bar ( 80psi)

^{_{Subscribers  do not see these advertisements}}

 

[Billggski]

Michelin always give 5.5 bar rear axle pressure for CP motorhome tyres to cover themselves. They assume the moho's will be running, and standing, with high loads, and may well be unintentionally overloaded (with wine?) at times.

 

[sdc77]

As an example. .
I have conti 4 seasons 2
Front 1720 45psi
Rear 2220 62psi

 

[DL42846]

As an example. .
I have conti 4 seasons 2
Front 1720 45psi
Rear 2220 62psi

Just as a matter of interest, where did you get those recommended pressures from?

^{_{Subscribers  do not see these advertisements}}

 

[sdc77]

Just as a matter of interest, where did you get those recommended pressures from?

Continental

 

[funflair]

Hi, I have been trying to get my head round the figures you have suggested and I'm having difficulty. It is first thing in the morning here and I have only had one cuppa. According to your calculations what would be your recommended tire pressures based on front axle weight 1440 kg, rear 1880 kg on the Michelin camper tires. I think the max pressures on them are 5.5 bar ( 80psi)

Good morning

Front would be 46psi and rear 60 psi based on 116 load rates tyre and 80psi max,

I would treat those figures as a minimum as more is better for a tyre than less is.

Martin

 

[funflair]

Michelin always give 5.5 bar rear axle pressure for CP motorhome tyres to cover themselves. They assume the moho's will be running, and standing, with high loads, and may well be unintentionally overloaded (with wine?) at times.

I can understand that but you should be fair to yourself when you go to the weighbridge and use a fully loaded figure.

Martin

^{_{Subscribers  do not see these advertisements}}