Re: Tyre Pressures

by Guest Mon Jan 10, 2022 9:43 am

Caraman wrote:
Molly3 wrote:I use the pressure stated on the door post 70 f 80 r cp tyres straight answer ok
For those that don't understand tyre pressures there is something to be said for the simplicity of using the axle MTPLM pressures shown on the door post, providing they are for the right type and size of tyre. However, for A-S coachbuilt conversions it will result in grossly overinflated front tyres but even that is probably better than having under-inflated tyres.

Simplicity was what I was striving for and what happens in the real world

by Guest Mon Jan 10, 2022 9:45 am

Paulmold wrote:OK, I had a Nuevo, 2006 so same base vehicle as Bigplumbs. I had Michelin Agilis Camper tyres. Michelin, if you ask them , will tell you the rears should be 80psi regardless of axle weight. I actually ran mine at 60 front and 65 rear, this was because at 80 my fillings would have shaken out. That could be classed as grossly under inflated but back then tyresafe did not go with the 80psi as they do now, they went by axle weight and 60/65 was what they recommended back then for camper tyres. So there you have an actual pressures as requested.
I've now changed van to a Sussex which again had Michelin Agilis and again I ran it 60/65 for comfort. That is also the pressures shown on door pillar. I've recently changed tyres to van tyres instead of campers and again 60/65 gives a comfortable ride.

Many thanks Paul great answer and very helpful to me.

by bikeralw Mon Jan 10, 2022 10:10 am

I have the same model and year of van as yours. New tyres fitted by our local Selecta branch a couple of years ago. Nitrogen filled (I didn't ask, so they dropped the charge). Pressures of 60 front, 70 rear, not far off the same as Paul.
By the way, you'll know different pressure gauges can vary wildly in their readings. I have three, one analogue and two digital, the difference between the lowest and highest is about 10%!
Al.

by Paulmold Mon Jan 10, 2022 10:45 am

If anyone wants the Tyresafe pressures by axle weight for Camper tyres (pre the 80psi current recommendation) the earlier listing as mentioned in my post above , it can be found here...

https://www.autosleeper-ownersforum.com/t3335-motorhome-tyres

If you don't want to weigh your van, then by using the maximum axle weights from your weights plate under bonnet, you will at least know the pressures for your van were it to be loaded to the max.

by Guest Mon Jan 10, 2022 11:42 am

bikeralw wrote:I have the same model and year of van as yours. New tyres fitted by our local Selecta branch a couple of years ago. Nitrogen filled (I didn't ask, so they dropped the charge). Pressures of 60 front, 70 rear, not far off the same as Paul.
By the way, you'll know different pressure gauges can vary wildly in their readings. I have three, one analogue and two digital, the difference between the lowest and highest is about 10%!
Al.

Nitrogen Filled....... Never heard of that before...... What is that all about

by Cymro Mon Jan 10, 2022 12:16 pm

You may find this helpful:

https://www.autosleeper-ownersforum.com/t1882-nitrogen-instead-of-air-in-tyres?highlight=Nitrogen

by Caraman Mon Jan 10, 2022 12:17 pm

Paulmold wrote:If anyone wants the Tyresafe pressures by axle weight for Camper tyres (pre the 80psi current recommendation) the earlier listing as mentioned in my post above , it can be found here...

https://www.autosleeper-ownersforum.com/t3335-motorhome-tyres

If you don't want to weigh your van, then by using the maximum axle weights from your weights plate under bonnet, you will at least know the pressures for your van were it to be loaded to the max.

Paul - the advice and figures given in your link are badly out of date.

TyreSafe now recommend a cold tyre pressure for an axle mass that is 10% higher than the actual axle mass. The figures in your link do not include this important safety margin, which is to compensate for among other things uneven loading across the axle which is present in all motorhomes and camper vans. Peugeot apply similar safety margins when they set the cold tyre pressures for each axle's MTPLM. As you know, TyreSafe also recommend that the ETRTO's somewhat controversial advice is followed to set the cold pressure of all single fitment rear CP tyres to their maximum permitted level of 5.5 bar (80 psi), regardless of the axle mass.

The standard Boxer has a relatively agricultural suspension especially at the rear, which unfortunately gives it a harsh ride. The suspension can be made to appear more compliant and therefore comfortable by lowering the tyre pressures but this is a dangerous ploy if it results in any tyre having insufficient air in it to support its load.

by Caraman Mon Jan 10, 2022 12:43 pm

Bigplumbs wrote:
Caraman wrote:
Molly3 wrote:I use the pressure stated on the door post 70 f 80 r cp tyres straight answer ok
For those that don't understand tyre pressures there is something to be said for the simplicity of using the axle MTPLM pressures shown on the door post, providing they are for the right type and size of tyre. However, for A-S coachbuilt conversions it will result in grossly overinflated front tyres but even that is probably better than having under-inflated tyres.

Simplicity was what I was striving for and what happens in the real world

If you don't know your axle masses and Peugeot's tyre pressure label on the passenger door post is for CP tyres and states 5.0 bar front and 5.5 bar rear, go with these pressures. It may be less comfortable than your current pressures but better to be safe than sorry.

by Suppersready Mon Jan 10, 2022 1:22 pm

I use the up to date tyresafe guide, only I put the actual laden rear axle weight of my van into the front tyre pressure section. This gives a tyre pressure of 66 psi, with this being a satisfactory pressure for the front axle I cannot see why it would not be so for the rear especially given that the front tyres are under a lot more stress than the rear ( steering, driven wheels, higher breaking force )
I then input the actual weight of the front axle into the front tyre section to obtain the recommended tyre pressure for that axle.
This seems logical to me … however I’m open to be challenged as I certainly do not want to be unsafe.

Niall

by Paulmold Mon Jan 10, 2022 2:39 pm

Caraman wrote:
Paulmold wrote:If anyone wants the Tyresafe pressures by axle weight for Camper tyres (pre the 80psi current recommendation) the earlier listing as mentioned in my post above , it can be found here...

https://www.autosleeper-ownersforum.com/t3335-motorhome-tyres

If you don't want to weigh your van, then by using the maximum axle weights from your weights plate under bonnet, you will at least know the pressures for your van were it to be loaded to the max.
Paul - the advice and figures given in your link are badly out of date.

TyreSafe now recommend a cold tyre pressure for an axle mass that is 10% higher than the actual axle mass. The figures in your link do not include this important safety margin, which is to compensate for among other things uneven loading across the axle which is present in all motorhomes and camper vans. Peugeot apply similar safety margins when they set the cold tyre pressures for each axle's MTPLM. As you know, TyreSafe also recommend that the ETRTO's somewhat controversial advice is followed to set the cold pressure of all single fitment rear CP tyres to their maximum permitted level of 5.5 bar (80 psi), regardless of the axle mass.

The standard Boxer has a relatively agricultural suspension especially at the rear, which unfortunately gives it a harsh ride. The suspension can be made to appear more compliant and therefore comfortable by lowering the tyre pressures but this is a dangerous ploy if it results in any tyre having insufficient air in it to support its load.

So what made Tyresafe change their figures? Wouldn't be that it's sponsored by the major tyre companies including Michelin ? Cynical? Me?

by Caraman Mon Jan 10, 2022 4:28 pm

Paulmold wrote:
Caraman wrote:
Paulmold wrote:If anyone wants the Tyresafe pressures by axle weight for Camper tyres (pre the 80psi current recommendation) the earlier listing as mentioned in my post above , it can be found here...

https://www.autosleeper-ownersforum.com/t3335-motorhome-tyres

If you don't want to weigh your van, then by using the maximum axle weights from your weights plate under bonnet, you will at least know the pressures for your van were it to be loaded to the max.
Paul - the advice and figures given in your link are badly out of date.

TyreSafe now recommend a cold tyre pressure for an axle mass that is 10% higher than the actual axle mass. The figures in your link do not include this important safety margin, which is to compensate for among other things uneven loading across the axle which is present in all motorhomes and camper vans. Peugeot apply similar safety margins when they set the cold tyre pressures for each axle's MTPLM. As you know, TyreSafe also recommend that the ETRTO's somewhat controversial advice is followed to set the cold pressure of all single fitment rear CP tyres to their maximum permitted level of 5.5 bar (80 psi), regardless of the axle mass.

The standard Boxer has a relatively agricultural suspension especially at the rear, which unfortunately gives it a harsh ride. The suspension can be made to appear more compliant and therefore comfortable by lowering the tyre pressures but this is a dangerous ploy if it results in any tyre having insufficient air in it to support its load.

So what made Tyresafe change their figures? Wouldn't be that it's sponsored by the major tyre companies including Michelin ? Cynical? Me?

The figures used by TyreSafe and all of the tyre manufacturers are the ETRTO figures which have not changed. What appears to have changed is the advice to use the ETRTO figure for an axle mass that is 10% higher. The reason for this advice is given on the current TyreSafe webpage. It is largely because of uneven loading across the axle but also because axle masses can increase after they have been measured. This could be caused by extra load, the removal of load behind the rear axle which will increase the front axle mass or simply moving the load around. There is also a risk that a tyre's pressure will have dropped since it was last checked. For all these reasons and because it is more dangerous for a tyre to be under-inflated than overinflated, it is best to use a cold tyre pressure that is slightly higher than it needs to be even though it may cause a harsher ride.

by Caraman Mon Jan 10, 2022 5:08 pm

Suppersready wrote:I use the up to date tyresafe guide, only I put the actual laden rear axle weight of my van into the front tyre pressure section. This gives a tyre pressure of 66 psi, with this being a satisfactory pressure for the front axle I cannot see why it would not be so for the rear especially given that the front tyres are under a lot more stress than the rear ( steering, driven wheels, higher breaking force )
I then input the actual weight of the front axle into the front tyre section to obtain the recommended tyre pressure for that axle.
This seems logical to me … however I’m open to be challenged as I certainly do not want to be unsafe.

Niall

Niall,

I don't know if you have Continental Tyres but if you don't it doesn't matter. Their Databook:

http://blobs.continental-tires.com/www8/servlet/blob/85806/69977261017e17f2a1dc8054655a4bcf/download-technical-databook-data.pdf

shows the ETRTO figures used by all tyre manufacturers and TyreSafe even though they appear to be Continental figures. Conveniently it shows the ETRTO's rear CP tyres pressures before the ETRTO stipulated that all rear CP tyres should be inflated to 5.5 bar. This shows that rear CP tyres should have higher cold pressures than front CP tyres of the same size. In 2020 Continental explained to me why this is so but I can't find their e-mail. Can I suggest you contact Continental to find out the reason. If you are using front CP tyre pressures on your rear CP tyres they will be under-inflated. You could also ask Continental about the ETRTO's recommendation to use 5.5 bar which is reflected in TyreSafe's on-line calculator and the TyreSafe recommendation to set a cold tyre pressure for an axle mass that is 10% higher. I discussed this on the phone with Continental's technical director in 2020. He was very helpful and supported TyreSafe's 10% recommendation but not the ETRTO's recommendation that all rear CP tyres should be inflated to 5.5 bar regardless of axle mass.

by IanH Mon Jan 10, 2022 5:11 pm

5 motorhomes, 2 x Warwick Duo, 1 x Eribacar, 1 x Harmony, this now Exec....all at 60psi all round no known problems.
Each to their own.
My C130 Hercules could be anything from 85000lbs all up weight to 155000lbs, all same tyre pressure............but let's not go there, losing the will to live as it is! wave

by Guest Mon Jan 10, 2022 6:10 pm

IanH wrote:5 motorhomes, 2 x Warwick Duo, 1 x Eribacar, 1 x Harmony, this now Exec....all at 60psi all round no known problems.
Each to their own.
My C130 Hercules could be anything from 85000lbs all up weight to 155000lbs, all same tyre pressure............but let's not go there, losing the will to live as it is!

Now that is what I like Simplicity....... All that other stuff is well quite beyond normal mortals who quite frankly just want to put some puff in their Tyres

by Guest Mon Jan 10, 2022 6:13 pm

As it happens I just had to have 2 new Tyres on my Landy Discovery... While the manager of the Tyre company was putting them on I asked him about Nitrogen..... The look on his face said it all. Further he said that at the moment it takes them about 2 mins to pump up a tyre.... With the Nitrogen system it takes them 14 mins.... He said he will loose at least 4 - 5 customers a day doing that. He also said that in tests the Nitrogen in the tyres after a few weeks was a much lower percentage then when put in.... Go figure.

Quite honestly this is all over complicating what was and still can be simple I suspect just so someone can make some money.

KISS

by Kemerton-bath Mon Jan 10, 2022 6:33 pm

Bigplumbs wrote:
Kemerton-bath wrote:The subject of tyre pressures is covered exhaustively on here, so if you’re not satisfied with some of the responses you’ve had then you could do your own research using the search facility.

Tim
Or people could just answer the simple question asked

Why should they, when as previously, you're just plain rude and sarcastic?

by Guest Mon Jan 10, 2022 7:27 pm

Kemerton-bath wrote:
Bigplumbs wrote:
Kemerton-bath wrote:The subject of tyre pressures is covered exhaustively on here, so if you’re not satisfied with some of the responses you’ve had then you could do your own research using the search facility.

Tim
Or people could just answer the simple question asked
Why should they, when as previously, you're just plain rude and sarcastic?

But they did. Do you perhaps think your comment above is rude

by **roli** Mon Jan 10, 2022 8:07 pm

Nitrogen or to be technically correct Oxy Free Nitrogen doesn’t take any length of time to inflate tyres that’s including aircraft tyres

The owner of this forum nor I will not tolerate arguments like this on the forum. I have seen enough and think the complaints I have received justify locking or deleting this thread. And if necessary blocking the main offender.

by oldfred Tue Jan 11, 2022 11:04 am

Oh dear - I can understand why some topics might end up in a heated exchange but on our friendly forum it takes only tyres and batteries confused0

by Caraman Tue Jan 11, 2022 12:52 pm

IanH wrote:5 motorhomes, 2 x Warwick Duo, 1 x Eribacar, 1 x Harmony, this now Exec....all at 60psi all round no known problems.
Each to their own.
My C130 Hercules could be anything from 85000lbs all up weight to 155000lbs, all same tyre pressure............but let's not go there, losing the will to live as it is!

I would have thought that the specification for an aircraft tyre including its cold pressure is all about the high stresses involved in landing and therefore the aircraft's maximum landing weight which is often less than the maximum take off weight. For this there can only be one pressure. There is nothing to be gained by lowering it for lighter landings. Road vehicle are different because for optimum performance they require different tyre pressures for different maximum axle loads as per the ETRTO figures with a bit added on.

by jwells Tue Jan 11, 2022 1:27 pm

Aircraft tyres are also checked before and after flight usually by a trained technician working to set figures, not by someone who thinks that they can do whatever they feel like - unless it's the pilot of course!!!

by Molly3 Tue Jan 11, 2022 5:13 pm

I wa told years ago nitrogen gas is used on racing and track cars , then someone decided to market it in tyre shops and motoring shows , targeting boy racers as used by xxx racing team ,just a a way of Inflating the bill ,

by Bilbobaggins Tue Jan 11, 2022 6:29 pm

A normal air pump will deliver about 80% nitrogen ie the concentration in normal air. Tyre shops used to say that filling with nitrogen reduced leakage and maintained pressure longer. Haven't been offered it for 3 to 4 years so guess they have been rumbled that it was a profit making scam

by BornAgain Wed Jan 12, 2022 8:41 am

I reduced the front pressures on my Broadway to 3.25 bar which was correct for my axle weights. That meant living with a low Tyre pressure warning (unable to reset) but at considerably improved ride quality. Sold the van so was unable to try it out on a long run. Awaiting arrival of a new Bourton when, no doubt, I’ll have the same dilemma but maybe the TPMS is easier to recalibrate on the Merc.

by merv Wed Jan 12, 2022 9:49 am

I noticed that in last year's brochure TPMS is absent from the panel van specs but present for coachbuilts. I think that at least one forum member with a new Symbol said that his new van didn't have TPMS.