What tyre pressures?

[Wh05apk]

I appreciate that tyre pressures are dependent on axle load, but what sort of pressures do you run?

The reason I ask is that we have a dethleffs trend 6767, which has been up plated to 3850kg, in the "fiat" part of the handbook it states ( for 225/75 r16cp) 5.5 bar / 79.8 psi whereas the dethleffs part states only 3.5/ 4.25 bar (51/62 psi ) this is based on the maximum axle loads of 1950/2000kg as I haven't been to a weighbridge yet, I will assume the maximum. This seems a massive difference, but have to admit the ride is much better.

 

[SMB]

This might help:

https://www.tyresafe.org/check-your-pressures/motorhomes/

 

[SMB]

My ducato based mh has the sticker indicating 5.5 bar front and rear as well but when I had Continental tyres they advised tyre pressures based on axle weights. I would go with the Dethleffs recommendations personally, I have my tyres at 48psi front and 62psi rear due to the much greater weight at the rear (weighbridge measurements )

 

[Wh05apk]

57/80 so same as fiat on the back, but a lot lower on the front, being slightly higher than dethleffs.

 

[Yorick]

It's free so get plenty in

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[Wh05apk]

I was concerned as 80psi seemed high, but other figures quoted on here seem to be about that, dropping to ty 50/55 seems a massive drop with better ride and no detriment to handling, there appears no bulg when stationary

 

[Sheddy]

Just checked our tag, on the plate weights, I will try again after we are fully loaded for our trip to Spain and been to the local weighbridge.

Cheers
Ed

 

[DJA]

Here is something I saved about tyre pressures by someone who contacted Continental for their advice.

Fiat Ducato, X2/50, tyres information: 215/70 R 15 CP 109R

Axle weights which resulted from a weighbridge...

Rear axle 1900kg (max 2000)
Front axle 1540kg (max 1850)
Gross 3440 kg (max 3500)

The following is the reply from Craig, the Product Support Engineer of Continental Automobil.

The pressures you require are as follows:

Front: 3.25bar - 47psi pressure applicable to a maximum permissible load of1590kg. 1850kg Max loading at 4bar - 58psi (1875kg maximum at this pressure)

Rear: 4.25bar - 61psi pressure applicable to a maximum permissible load of1970kg. 2000kg Max loading at 4.5bar - 65psi (2060kg maximum at this pressure)

As a general rule for pressures on this tyre, every 100kg added from the base figure of 1490kg at 3bar (43.5psi) will require an increase of 0.25bar(3.6psi) in pressure up to a maximum of 2060kg at 4.5bar (65psi)

We do get a substantial amount of queries regarding pressures. Unfortunately, there is a distinct lack of understanding on the subject which isn't helped by the apparent reluctance of coach-builders to specify the pressures required. Naturally, all pressures are dependent on load so providing any queries received contain the information requested, we can advise accordingly. I've helped a few other organisers of motorhome/camping clubs and associations in the past so we are all working to educating the consumers as to what is required. Hopefully this will provide a greater understanding for them.

 

[Wh05apk]

Thanks dja that is really useful and confirms the dethleffs figures, just wonder why fiat are quoting much higher?

 

[Emmit]

This comment from the bloke at Continental was enlightening.
" Unfortunately, there is a distinct lack of understanding on the subject which isn't helped by the apparent reluctance of coach-builders to specify the pressures required. "

" Naturally, all pressures are dependent on load so providing any queries received contain the information requested, we can advise accordingly."

These comments should, with any luck finally kill the notion that it's 80psi all round, regardless of the weight, size and No. of axles on the motorhome.

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[gerry mcg]

I think it depends on the brand of tyre fitted too.
I asked Michelin regarding the tyre pressures for my 3500kg Ducato PVC with 16" Agilas CP tyres - and Michelin recommended 65psi front / 80 psi rear for my 3500kg PVC with a 1650kg/1850kg F/R axle weight distribution on 225/75/R16C/CP Q 116 a Agilis Camping tyres
I posted this on a different thread a while back - https://www.motorhomefun.co.uk/forum/threads/tyre-pressure.136035/page-4#post-2299529

This was their reply

The Agilis Camping tyre boasts a long life by using the same technology as the Michelin Agilis van tyre range. It has a reinforced construction to enable the use of higher pressures, has 8 kerbing protectors built in to each sidewall to increase resistance of sidewall scuffing and is M+S (mud and snow) marked to give sufficient grip when occasionally travelling in difficult conditions such as unsurfaced roads, mud and snow.

The suggested tyre pressure for the rear of a motorhome running on the Agilis Camping is 80psi. This is due to the construction of the tyre with 2 casing plies enabling the use of higher pressures. Its 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 pressures however can be adjusted according to accurately weighed axle loads for a more comfortable ride and optimum performance. We at Michelin recommend 65psi to start with.

 

[Emmit]

Each to their own but I don't see Michelin paying for your teeth fillings being replaced when they get rattled out by having the rear tyres inflated to 80psi.

 

[Emmit]

Thanks dja that is really useful and confirms the dethleffs figures, just wonder why fiat are quoting much higher?

Michelin quote 80psi regardless. If they made pram tyres they would quote that figure.

 

[DJA]

I assume that Michelin may quote higher pressures for standard Van tyres as they do not have the stiffer walls that the Continental Motorhome tyres have. I also knew that when people have contacted Michelin to get their recommendations for pressures on their Aqiilis tyres they, as confirmed by gerry mag, quote higher pressures going as high as 80psi.

When we got our van I had the sticker on the door post with recommended tyre pressures and they are much higher than we now use based on Continentals recommendations. It would appear that standard White Man Van tyres seek higher pressures, which may explain their speeds as they are virtually floating.