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Hi Everyone ,

Can i just say thanks to those of you who recently had this discussion, as a result I went out to find that the pressures in our 6 month old Swift 590RL had been set at 80psi, which on looking at the tyre wall is the pressure for fully loaded max weight, which we have never yet been near, no wonder I thought the ride was rough(she thought it was my driving).
I have now reduced them all to 60 and 65. So be warned even when they arrive new - check them.

ian and Col.

Ps, Its nice to be back.
 

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Hi colian, I think you will find the handling quite different and the swaying (change direction) when a lorry passes or you pass it quite a lot less, and very much smoother.
Jon.

edit - correct some missing text.
P.S. sob sob :( I don't like being a newbie again!
 

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I have just taken delivery of a new van based on a Fiat 2.8 with Michelin X Camping tyres.
The handbook gives 5.0 pressure all round, irrespective of load.
The van had significantly lower pressure and after inflation to recommended pressure it seemed to drive very well but many more rattles were obvious!!
If I set it at 65/60 that might be a fair compromise but is it safe and will it be running at opitimal efficiency. Am also concerned that if an accident were to occur would there be problems with pressure below recommended.
It's a CI Mizar GTL Living - any views/experience out there??

Best wishes

alan
 

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got my auto-sleeper nuevo last friday, checked the tyres (michelin xc camping) and yes these were at 80 psi, the sticker in the door shuts gives 79.5 psi all round, acting on recent discussions on this forum i have reset to 60 psi front and 65 psi rears. in addition i have sent off an email to Michelin asking for advice and giving the mtplm and axle weights. they have acknowledged my email and said it has been passed to someone who will get back to me shortly. as soon as i get this info i will pass it on to this forum.
 

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The door pillar sticker on my van is also 79.5 psi all round. Michelin have consistently given lower rating then the chassis manufacturer for previous 'vans.

For my current one I E-mailed Michelin for info based on maximum rated axle-loadings for the 'van, 3850kg MTPLM and 215/75 R16C *Camping* tyres.

Following was the response:

==


Thank you for your recent e-mail.

The pressures that we would recommend based on the loads quoted are as follows;
-

Front axle 1850kg - 60psi
Rear axle 2120kg - 64psi

====

Which is considerably lower than Fiat's rating.

I've dropped mine to some 5psi all round higher than these recommendations, and keep a copy of the eMail in my handbook in case I get pulled by the boys in blue.
 

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Glad you are got pressures sorted out and for posting. I am collecting all this information and plotting on a graph. Yep! your info sits spot on my line so maybe time I published a copy on here as a guide. Will need to work out how to do it but should nt be difficult.
However I could do with another pressure1400kg axle loading for 215/75 C 16 tyres to confirm if anyone has received info from Michelin. I have a colleague who is fairly senior at Michelin factory and will give him a ring this week to ask why they do not publish a graph or data themselves and see if I can prise more data out of him, or ask him to find out. Expect I will be told it is to do with liability and people reading wrong/out of date info and blaming them.
Jon.
 

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The pressure given on the tyre is a the tyres Maximum Loading. AFAIK, it isn't illegal to inflate under this if the loading is less.

The lower figure given by Michelin will give a more comfortable ride, and if they are much underinflated it will show in the handling .

As a matter of interest, My "Nuevo", (Which is an early version) has 15" wheels, and was fitted with Firestone CV3000 tyres of size 195 70 R 15
At full load, these are running near their max. loading, so I tried to get a set of Michelin XC Camping tyres but couldn't find anyone who could supply me with them. I contacted A/S and was offered Michelin XCA tyres which are of a lower rating. They were overpriced though, so I have been looking for an alternative.

Are the 16" wheels on your Nuevo a standard size? If I fit 215 70 R 15 on my van, the increase in dia. means my Speddo will read approx 3 mph low at 70 mph. If I bought new wheels ( I almost treated myself to a set of alloys) and fitted the size tyres you have, my speedo would read approx. 8 mph low at 70 mph!

Will let you know what I find.
 

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Hi,

tyre pressure is always a balance between comfort and safety:

If a tyre is underpressured in relation to the load put upon it, wear will increase dramatically and it might blow (preferrably at high speed :( ). Keep in mind: Tyres blow because of underpressure and not of overpressure! Sounds paradox, but is true.

If tyre pressure is higher than necessary for the load, but still within specs, then this is just a matter of comfort, not of safety. So the Motorhome manufacturers (and probably Fiat as well) tend to play safe and therefore recommend a higher pressure.

Also keep in mind that many motorhome(r)s have a certain tendency towards overloading. So if you really want to go below recommendations with your tyre pressure, then take the fully laden van to a weighbridge, check the real load per wheel(!), add around 10% safety margin and then select the appropriate pressure based on this.

Best Regards,
Gerhard
 

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I am curious as to what the legal, in terms of your average plod, aspect would be. I have never been stopped for having my tyre pressures checked, but I understand with cars they do seem to have a view as to what they should be inflated to. I am thinking here should everyone who uses a different pressure to the base vehicle spec. get a letter (or communication of some kind) from the tyre manufacturer?
I also find that 60 and 65 psi suit the ride and handling of our Autostratus but have often wondered what would happen if we were stopped and they were checked.
Does anyone know?
 

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i have had my reply from michelin with the tyre pressures for my nuevo-es (michelin xc camping tyres 215/70 r15) the axle weight i gave them were 1750k front and 1900k rear mtplm 3400k. the correct tyre pressures for me are 54psi front but to allow +10% to take in weight transfer on braking so 59psi on front and 59psi on the rear. they also stressed the need to go to a weighbridge and check it fully loaded. note i say these are the tyre pressures for my A/S nuevo i suggest that everyone should contact their relevant tyre manufacturer and get their personalised tyre pressure and with a copy of the email reply should feel confident that any inquiry is covered.
 

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Had not realised that they were now producing "low-profile" tyres in commercial sizes, following the trend with modern cars,... am a little out of touch ?... suppose that it was inevitable.

The point I am making is that, the lower aspect tyres,... (70,-60,) %. aspect ratio,.. while offering superior handling and stability,... will afford this at the cost of comfort,... ie; less air-cushion between you and the road

So perhaps not just a matter of tyre pressures,... [rather the eternal quest for better/faster handling on the part of the manufacturer.)
I](my ancient Talbot runs on standard "high-profile" 185 X 14 @ 60psi,...)[/I] though I run them at 50psi quite happily.

Alan
 

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After a 'reasonable' drive of some distance, including motorway speeds if possible, check the relative temperatures of your tyres by placing the palm of your hand on the tread as soon as you stop.

Cold - tyres are possibly overinflated.
Slightly warm - probably about the correct pressure.
Very warm, or hot - tyres are possibly underinflated.

I use 'probably' because this is just a very rough guide to help keep you out of the danger areas. Boff is right about the 'under-pressure' aspect causing blow-outs, and heat build-up is the first indication that something's not right.

Some tyres run warmer than others, so this is a very rough guide. It's a good safety tip, though, if you're on a run without a pressure gauge to hand.
 

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Hi Chaps,
DO also bear i mind that over inflated tyres (as wil underinflated) will also wear much more quickly as they will slip more, especially the driven wheels.
But on the dangerous aspect although I agree an under inflated tyre can get very hot cause failure, equally an over infalted tyre can sustain damage if you were to mount a kerb or other object (large stone). The stress in the textyle layers can be enormous. Hence never ever mount kerbs like you see delivery drivers doing all the time.
But, and much more relevant is your massively increased braking distance especially in the wet. 80psi and unladed - have you tried stopping quickly in the wet? - you might get quite a fright compared to the correct pressure or even at 75psi which is still 10 psi over most max required pressures.
On the subject of max pressure if you have a standard Fiat chassis you should be no more than 60 in the front and 65 in the rear or you are overloaded. I suppose if you want to allow for imbalances across the axles you should allow an extra few psi but usually vehicles are pretty well balanced across the width and allowed for in the recommended pressures.
Right, that's my tuppence worth for tonight for what it is worth.
Jon.
 

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Here is another one for you.

------------------------------------------------------------------

The pressures that we would recommend for your motor home fitted with 215/75 R16C XC Camping TL 113N tyres are as follows; -

Front axle at 1400kg = 45psi.
Rear axle at 1900kg = 57psi.


Once again thank you for your interest in Michelin.

-------------------------------------------------------------------------

I bet Michelin are busy with us lot.

Ralph
 
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