# Tyre pressures



## eddied (May 9, 2005)

:? 
Would appreciate some expert advice on this point. Recently decided to change 4 year old low mileage Michelin tyres 215/75/16 on my Fiar Ducato 2.8 based Bessacarr E645; since cracks/bulges beginning to show due to age/exposure to sun etc.
A well known nationwide dealer fitted Avon Avanza tyres, and I find they are inflated to 65 p.s.i. whilst the FIAT handbook/doorstickers reccomend 79.5 p.s.i for the original gear.
Unable to find much information re Avon on the web. 
Tks - eddied


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## 89146 (May 15, 2005)

I am far from being an expert but sought advice on tyre pressures last year since the dealer seemed unable to tell me what the pressure should be and the handbook (being in German) was not much help. :roll: 
I have a Hymer 524 on a Fiat Ducato 2.8 TD base.
The advice I was given - and the van drives beautifully on this - was to inflate all four to 70psi. The make of tyre didn't enter into the debate so either a) everyone assumed that I had the "standard" type fitted or b) it didn't make a difference. :? 
I would be surprised if the make made any difference and 65psi does seem a little low; maybe these Avons a different specification to the original? If so, are they still appropriate for the vehicle?


Gill


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## rednev (May 10, 2005)

HI i have a swift royale 630 on a fiat 2.5tdi I run fronts at 60psi and rear at 65psi fully loaded and the van runs fine and the tyres look good the mh is not small at over 23 feet paul.


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## BrianR (May 1, 2005)

It sounds as if the original tyres were Michelin XC Campers, if the pressure was 79.5psi. To find the correct pressure for your current tyres, weigh your vehicle fully loaded (including passengers), front and back axles separately, and then contact Avon to find the recommended pressures for your tyres. The web address is www.avontyres.com


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## 89202 (May 16, 2005)

Hi,

if you have an ALKO chassis with Michelin XC tyres : 5,0 bar on all the wheels on the original chassis 5,5 bar.

Over 4,7 bar you need metallic valves for Michelin XC tyres.

for info,

duc


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## 89057 (May 12, 2005)

As tread wear is not a consideration ( tyres changed well before limit due to deterioration). I found that experimenting with the pressures between 55 & 75 psi, I got my own favorite ride. A balance between reasonable roadholding, comfortable ride & minimal pot rattling  

As it is a personal preference thing, experiment & find the best for you & your van, it's well worth the effort 8) 

If on the other hand your peace of mind comes from spec's & other peoples opinions, there will be info from the converter available somewhere on the web :wink:


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## Anonymous (Nov 10, 2000)

I was told, having changed from mich to Marshalls that it is best to pump all tyres up to the max as stated on the tyre wall for motorhomes.

Since then, I have won a first and two second places in the Hop Skip and Jump competiton. It cuts down on tyre wear too as they are more often in the air than on the road.

Highly recommended.


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## Anonymous (Nov 10, 2000)

Eddied

Before inflating your tyres above the present 65lb I would advise you to check the max tyre pressure permitted on your new tyres, it should be written on your tyre sidewall.

I had 2 new 12 ply tyres fitted and inflated to 70PSI, ran them for 3 months then whilst checking the tyre pressures found I had been fitted [email protected] and [email protected] ply, I obviously had the error put right FOC, but at the time I noticed that the 10ply tyre was only rated with a maximum 65PSI, so it's worth a check.

KenS


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## Hymer634 (May 9, 2005)

Don't forget also that pressures above about 60 or 65b psi require special bolted in valves not the normal push fit rubber ones.

Normal tyres also tend to require lower pressures than the Michelin Camping tyres.

The only safe way is to use a weighbridge and then contact the manufacturer of your particular tyre - they are usually very helpful.

Alan.


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## Brambles (May 12, 2005)

Hi,

Agree with BrainR. Contact manufacturer. Tyre pressured are critical and will vary from one vehiocle to another depending on weight. Best to get M'home axles weight when fully laden.

A lot of people are setting tyre pressures to maximum and from past discussions on these forums Michelin were astounded to hear m'home manufactures where recommending 80 psi as that is the maximum permisable pressure.
I contacted Michelin re mine and was given pressures of 46 and 54 rear but that is meaningless as yiru weights will be different. Made an incredible difference to handling, steering and comfort though.


Stil think pussers reply is the best LOL pusser.


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## eddied (May 9, 2005)

Thanks to you all for helpful replies. Have had a good ride at the current 65 p.s.i. but will maybe try 70.
cheers - eddied


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## fdhadi (May 9, 2005)

I have a Knaus Motorhome, 2.8 Fiat Ducato.
The Fiat handbook says 5.5 bar.
The Knaus handbook 4.5 bar.

As the Motorhome was added to the Fiat and then weighted & tested, you need to work from the converters recommended pressures.
Fiat didn't know at the time of build what body was to be fitted.

We have air ride suspension fitted, we bounced for 4500 miles at 5.5 bar.
Changed the pressures to 4.5 bar and noticed the difference after 10 miles, felt like a new motorhome.

Hope this makes sense.

Frank


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## 95075 (May 1, 2005)

Have recently bought a Hymer 584 2.8 JTD Fiat. It was fitted with 215/75 x 16c Michelin Campers, the previous owner ran @ 75lbs rear 70lbs front plus [email protected] 

It drove OK but very hard and also light on the front. We fully loaded it today, bikes, water, fuel - dog the lot the & went to the local weighbridge.

Results......Front axle 1500Kg (750 per wheel)
Rear axle 1900Kg (950 per wheel)
Total weight 3400Kg on a 3500kg chassis

I phoned Michelin technical dept and gave them the figures and they recommended the following pressures.

Front ..........50lbs 
Rear............60lbs 

This I felt was too low so I settled on 54lbs Front and 64 Lbs Rear leaving the airride at 35lbs.

It certainly is much quieter on the road, not so light on the front steering and doesn't roll excessively.

Michelin also said that their Agilis 81 was a suitable tyre for the Hymer and the pressures should be the same as the Camper tyre.


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## Brambles (May 12, 2005)

Hi Hares7.

Thanks for posting your info from Michelin. I have been over the last year trying to draw a graph from info I pick up from here and there on pressures for the 215/75 x 15. Intersting your values for the 2715/75 x16 also sit fairly close to my chart.
Has anyone else got pressures for tyres from Michelin (or other) and like to post. 
Like you I thought values were a bit low so put in an extra 5 psi. If I put in an extra 10 psi it really starts to have a negative effect on handling and front wheels are easy to spin. LOL spin starts in a Motorhome at the traffic lights - whatever next :roll: 
Over inflating will tend to reduce handling but will give better fuel consumption. Higher presures can also give reduced tyre wear but ther comes a point when tyres will lose contact and wear much quicker. Also the higher the pressure the higher the stress especially when driving over rough ground or bumps (never drive up a kerb on any tyre - you risk damaging the carcase and more likely to get a bulge when the tyre is older)
Too low a pressure will also cause tyre wear, increased fuel comsumption and tyres will run hotter which is also bad news for a tyre.

Now the important bit - do run your new tyres in. Keep speeds down for 1st thousand miles or so. An incredible heat is generated with new rubber as it is still not fully cured and is softer. The tyre which in its 1st few thousand miles is abused that is more likely to get bulges blow outs etc when it gets older.
sorry, I am rambling on now as it is getting late - will shut up
Jon.


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## 88790 (May 9, 2005)

What would be really useful is that if all the folks that have contacted the tyre manufacturers could post saying what van they have, what tyres and the pressures they were recommended to use!

This information would be helpful to a lot of us I am sure!


John 8)


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## Brambles (May 12, 2005)

Hi,
I think jabber's suggestion is a good idea.


I have been looking into the situation regarding tyre pressures and what strikes me is no one with a new FIAT or MERC should have front tyre pressures above 60 psi. 

How do I come to this conclusion?
Based on figures I have been given so far, and plotting on chart.
Max axle load for front wheels on FIAT or MERC chassis 1850 kg (ducato 15Q is 1750)
Look at chart - 58.5 psi .
(for FIAT 15Q - 215/70 x 15 tyres it is 56psi on chart)

What i do not know is what it is for 205/70 x 15 tyres. 

Conclusion, if you need more than 60 psi in the front your vehicle is over its max laden weight.

Now for the Rear. All depends if you have an ALKO chassis or not.
For standard FIAT chassis 18Q - max laden weight allowed 2120kg= 66psi
For 15Q - max laden weight allowed 1900kg = 60 psi

So this really makes me wonder how many people are driving around iwth over inflated tyres. Also why Michelin were astounded M'home manufactures recommend 80 psi. But what i find interesting is why do Michelin not publish a chart. Maybe liability reasons, who knows! Or because if the publish and then decided different pressures are correct they are liable to inform every one who has tyres. I don't know why, but they only tell you the pressures for the weights you ask then about. 

Take all data I have written above as guess work - I would need to collate more data before being confident values are 100% correct - but does high light the max tyre pressure rating label on Fiat vans (and handbook) is misleading.


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