# Tyre pressures



## Herman (Aug 2, 2020)

Finally after 3 years of ownership I decided to drop the tyre pressures on the back axle from 70PSI to 65PSI and wow! what a difference to the internal travel noises, the bathroom door being the main one not rattling any more. I'll try dropping the fronts by 5PSI next.

What pressure do others run their tyres at.


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## Snapster (Aug 2, 2020)

Ours are supposed to be 79 psi all round. I have run them at around 68psi too and not noticed any difference in the ride quality. What I did notice though ( having a Tyrepal kit fitted) that the tyres run much cooler at the recommended pressures.


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## Nigel L (Aug 2, 2020)

After nearly 4 years of wondering what pressures should I be running, after reading all sorts of suggestions from various posters, I finally got round to going to a weighbridge and had the axles weighed. Then dropped an email off to Continental for the correct pressures.
what an eye opener! Have had the 5-5 bar in, as recommended by both the dealers and also on the sticker inside the door on the van. After speaking to Continental, am now running 3-25bar in the front, and 3-5 bar in the rears, and what a difference it has made to the ride quality.
Well worth the trip to the weighbridge, not only to get the pressures sorted once and for all, but also the peace of mind that I am also within the 3500kg overall weight restriction.


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## molly 2 (Aug 3, 2020)

I run at 5.5r   5.0f  bar as stated  on the door plate


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## harrow (Aug 3, 2020)

Only a point to consider, this summer temperature will increase tyre pressure in the sunshine


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## mark61 (Aug 3, 2020)

With so many people using TPMS's, would be interesting to see views on the old 4/6 PSI rule.
I know plenty regard it as rubbish, but if a tyre company like Cooper are prepared to mention it, it's probably worth noting.

https://www.coopertires.com.au/media/1400/cooper-drivers-guide-tyre-pressures.pdf


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## mfw (Aug 3, 2020)

I agree with Harrow outside temperature needs to be considered high tyre pressures are ok in the winter but in the summer pressures increase quite a bit especially if you do a bit of mileage on hot tarmac/roads


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## Snapster (Aug 3, 2020)

With our tyres at the recommended pressure, I noticed on a hot day travelling ( 300 miles on motorways last week) the pressures increased by around 8 psi. 
When we ran them at the lower pressures, temperatures went up by around 12 psi.


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## mfw (Aug 3, 2020)

You may find some of the recommended tyre pressures are max pressure for the tyres so worth looking at the tyre and seeing what the max pressure is for the tyre and then making your own decision on what pressure you want to use in them


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## RV2MAX (Aug 3, 2020)

In Australia we used work on 6psi rise  . So you check tyres cool before start of travel , after say 20 miles or so check again , there should be a 6psi rise , if more then they were underinflated to start , so say 8psi , you raise  start pressure by 2 psi  next time .    If rise is only 4 psi , then over inflated at start  so drop start pressure by 2 psi .  This works for a given load and for bitumen running .


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## wildebus (Aug 3, 2020)

harrow said:


> Only a point to consider, this summer temperature will increase tyre pressure in the sunshine


the same is true in the Winter as well   and the variation is actually a fair bit greater (A tyre temp once the vehicle has been running for 20 minutes or so is very unlikely to be any lower than any ambient air temp in the UK at any time of year)
in my RAV4 back in 2006 I used to inflate the tyres to the pressure needed, and would often get low PSI warnings in the morning when the ambient temp was very low - I don't think people appreciate just how much temperature affects pressure until they have a TPMS system.

I've never tried it myself but apparently doing a Nitrogen fill (rather than standard air) is meant to virtually eliminate that variation.


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## Wooie1958 (Aug 3, 2020)

The higher temperatures produced by the lower p.s.i. is simply down to the tyre deforming and reforming ( flexing ) more when in contact with the road.


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## harrow (Aug 3, 2020)

Wooie1958 said:


> The higher temperatures produced by the lower p.s.i. is simply down to the tyre deforming and reforming ( flexing ) more when in contact with the road.



A bit like after eating Christmas dinner


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## Deleted member 77519 (Aug 3, 2020)

Nigel L said:


> After nearly 4 years of wondering what pressures should I be running, after reading all sorts of suggestions from various posters, I finally got round to going to a weighbridge and had the axles weighed. Then dropped an email off to Continental for the correct pressures.
> what an eye opener! Have had the 5-5 bar in, as recommended by both the dealers and also on the sticker inside the door on the van. After speaking to Continental, am now running 3-25bar in the front, and 3-5 bar in the rears, and what a difference it has made to the ride quality.
> Well worth the trip to the weighbridge, not only to get the pressures sorted once and for all, but also the peace of mind that I am also within the 3500kg overall weight restriction.


Did you get written proof from Conti?. Just in case you get pulled in for a VOSA check. They will go with what is stated on the plate. Saves the hassle of having the vehicle impounded. I know this from a Professional point of view, and 'They' do not have any sense of humour
Plus it stops the attendant Police officer giving you a ticket for underinflated Tyres. Iff that happened you would probably have to attend Court with your evidence. All a load of faff to be avoided at all costs.


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## wildebus (Aug 3, 2020)

Do VOSA actually check Tyre Pressures on a private vehicle?   I can imagine they might be able to see an obviously underinflated tyre, but there is not a "one pressure fits all" tyre pressure to suit all circumstances - it depends very much on the loading of the vehicle and the type of driving.


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## colinm (Aug 3, 2020)

When we where stopped, about 15 years ago, they checked weight, but didn't notice them checking pressures. In my 'paperwork pack' I have the chart with axle loads and pressures as these are significantly different to the label.


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## Deleted member 77519 (Aug 3, 2020)

wildebus said:


> Do VOSA actually check Tyre Pressures on a private vehicle?   I can imagine they might be able to see an obviously underinflated tyre, but there is not a "one pressure fits all" tyre pressure to suit all circumstances - it depends very much on the loading of the vehicle and the type of driving.


Good point. They may not on a private vehical. I'd still like to carry written proof though, Police might check on a vehical inspection. They certainly would in a bad accident. As said Tyres pressures have to be adjusted for load as well, each and every trip. I actually try and get mine somewhere near, like Sundays blast, unloaded. Reduced pressures by 5 psi.
You would have to be pretty unfortunate for VOSA to check I think. Unless you got one of our lot, then it's fine tooth comb and magnifier glass time. They are Twats.


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## Millie Master (Aug 3, 2020)

Nigel L said:


> After nearly 4 years of wondering what pressures should I be running, after reading all sorts of suggestions from various posters, I finally got round to going to a weighbridge and had the axles weighed. Then dropped an email off to Continental for the correct pressures.
> what an eye opener! Have had the 5-5 bar in, as recommended by both the dealers and also on the sticker inside the door on the van. After speaking to Continental, am now running 3-25bar in the front, and 3-5 bar in the rears, and what a difference it has made to the ride quality.
> Well worth the trip to the weighbridge, not only to get the pressures sorted once and for all, but also the peace of mind that I am also within the 3500kg overall weight restriction.



If you do run your tyres with significantly lower pressures than those given in the owners handbook then make certain that you carry a copy of the email/letter you received from the tyre manufacturer with you, just in case you ever get stopped for a DVSA road side check where they will almost certainly test the tyre pressures and if they vary from those given by the vehicle manufacturer, then they might well prosecute unless you have proof that you have been acting responsibly.


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## Val54 (Aug 3, 2020)

Millie Master said:


> If you do run your tyres with significantly lower pressures than those given in the owners handbook then make certain that you carry a copy of the email/letter you received from the tyre manufacturer with you, just in case you ever get stopped for a DVSA road side check where they will almost certainly test the tyre pressures and if they vary from those given by the vehicle manufacturer, then they might well prosecute unless you have proof that you have been acting responsibly.


Good point, I have a copy email from Conti dropping our front axle spec from 80psi to 55psi, I'm surprised they gave a rear spec as per #3 as they usually will not risk giving a rear axle calculation because of comeback if the vehicle was then run at a higher load which potentially contributed to an RTA.


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## gettingolder2 (Aug 3, 2020)

If your tyre pressure is correct the wear acrossthe tyre will be even. If the middle of the tread only shows signs of wear the pressure is too high.
If the edges show signs of wear then the pressure is too low. However if the wear at the edges is not equal then the tracking is out regardless of the pressure.


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## Tookey (Aug 3, 2020)

gettingolder2 said:


> If your tyre pressure is correct the wear acrossthe tyre will be even. If the middle of the tread only shows signs of wear the pressure is too high.
> If the edges show signs of wear then the pressure is too low. However if the wear at the edges is not equal then the tracking is out regardless of the pressure.


Er, dunno, phone a friend please


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## molly 2 (Aug 3, 2020)

mfw said:


> You may find some of the recommended tyre pressures are max pressure for the tyres so worth looking at the tyre and seeing what the max pressure is for the tyre and then making your own decision on what pressure you want to use in them


Not so  if you check  15 inch vanco  camper tyres  it says max  pressure  60 psi   . That is for  American  Market  only


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## Deleted member 77519 (Aug 3, 2020)

I always thought the max pressure (indicated on the sidewall) was the maximum the tyre could safely take  allowing for expansion. Anybody?


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## colinm (Aug 3, 2020)

Hallmut said:


> I always thought the max pressure (indicated on the sidewall) was the maximum the tyre could safely take  allowing for expansion. Anybody?


No, for 'our' use it's not relevant.


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## trevskoda (Aug 3, 2020)

Mine say 85psi on side wall but i run at 65psi which is set on cool days,van dont ride nice at high pressure with little load.


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## Deleted member 77519 (Aug 3, 2020)

colinmd said:


> No, for 'our' use it's not relevant.


Ah, that clears it up, cheers.


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## molly 2 (Aug 3, 2020)

Hallmut said:


> Did you get written proof from Conti?. Just in case you get pulled in for a VOSA check. They will go with what is stated on the plate. Saves the hassle of having the vehicle impounded. I know this from a Professional point of view, and 'They' do not have any sense of humour
> Plus it stops the attendant Police officer giving you a ticket for underinflated Tyres. Iff that happened you would probably have to attend Court with your evidence. All a load of faff to be avoided at all costs.


Absolutely  correct , that is why  I run my van  at the plated  tyre pressure  ,  that is the correct  pressure .


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## Nigel L (Aug 3, 2020)

Millie Master said:


> If you do run your tyres with significantly lower pressures than those given in the owners handbook then make certain that you carry a copy of the email/letter you received from the tyre manufacturer with you, just in case you ever get stopped for a DVSA road side check where they will almost certainly test the tyre pressures and if they vary from those given by the vehicle manufacturer, then they might well prosecute unless you have proof that you have been acting responsibly.


Hi, thanks for that, yes, I have printed off a copy of the email from Continental, and keep it in the a Van.


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## Herman (Aug 3, 2020)

I'm going to have to go to a weigh bridge, Nigel has dropped from 80PSI to 50PSI on the back and 80PSI to 47PSI on the fronts that should make for a nice soft ride. But as others have said, once I now the laden axle weights i'll email the tyre manufacturer for the correct pressures and carry a copy of the email as proof.

Thanks everyone.


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## colinm (Aug 3, 2020)

Herman said:


> i'll email the tyre manufacturer for the correct pressures and carry a copy of the email as proof.



If it's Conti's they will give correct pressure front and rear, if it's Michelin they will give correct front pressure, but always give rears as maximum pressure.


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## trevskoda (Aug 3, 2020)

If there to soft the van may wollow in corners,be carefull.


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## Deleted member 47296 (Aug 4, 2020)

This link is to the Continental Data book 2017-2018 which is the latest I have and gives pressures for their tyres at various loadings.

https://blobs.continental-tires.com...MmVhMGU4YzlkYzZlMTE0YzQwNjE1NTM2MTczNDU2OTU=~

and this link is to the Tyresafe document which gives loadings more generally as well as an explanation of tyre markings

https://www.tyresafe.org/wp-content/uploads/2015/12/motorhome-leaflet.pdf

You might find them of interest.


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## Deleted member 8055 (Aug 6, 2020)

Val54 said:


> Good point, I have a copy email from Conti dropping our front axle spec from 80psi to 55psi, I'm surprised they gave a rear spec as per #3 as they usually will not risk giving a rear axle calculation because of comeback if the vehicle was then run at a higher load which potentially contributed to an RTA.


 and 50 front


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## Deleted member 8055 (Aug 6, 2020)

I too got an email from Continental reducing a bone jarring 80 all round to 60 rear and 50 front. I think manufacturers think that all motorhomes are stupid and will automatically overload. I also asked Continental regarding renewal of tyres after recommended 5/6 years. They replied that they have no such limits, but you should check condition every year for cracks etc. They also said there was no need to use metal valves as they would be inclined to break rather than flexing as rubber. So far I have had no problems with any of these recommendations after 3 years.


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## Val54 (Aug 6, 2020)

gisjbert said:


> I too got an email from Continental reducing a bone jarring 80 all round to 60 rear and 50 front. I think manufacturers think that all motorhomes are stupid and will automatically overload. I also asked Continental regarding renewal of tyres after recommended 5/6 years. They replied that they have no such limits, but you should check condition every year for cracks etc. They also said there was no need to use metal valves as they would be inclined to break rather than flexing as rubber. So far I have had no problems with any of these recommendations after 3 years.



I've had both metal and rubber valves fail on the rear axle, metal valves can eventually corrode on the seating which may lead to a minor leak, the rubber valve wouldn't hold pressure at 75psi and a very small leak would result in a drop to 60psi after a few weeks, which it then stayed at.


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## barge1914 (Aug 6, 2020)

Nigel L said:


> After nearly 4 years of wondering what pressures should I be running, after reading all sorts of suggestions from various posters, I finally got round to going to a weighbridge and had the axles weighed. Then dropped an email off to Continental for the correct pressures.
> what an eye opener! Have had the 5-5 bar in, as recommended by both the dealers and also on the sticker inside the door on the van. After speaking to Continental, am now running 3-25bar in the front, and 3-5 bar in the rears, and what a difference it has made to the ride quality.
> Well worth the trip to the weighbridge, not only to get the pressures sorted once and for all, but also the peace of mind that I am also within the 3500kg overall weight restriction.


I had exactly the same experience with Continental. Michelin however whilst accepting a reduction on the front will not relent on the 5.5 bar on the rears, even though the rear axle load is less than the front. Can anyone volunteer a rational reason why?


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## in h (Aug 6, 2020)

Hallmut said:


> I always thought the max pressure (indicated on the sidewall) was the maximum the tyre could safely take  allowing for expansion. Anybody?


No, it's the recommended pressure at the maximum rated load.


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## in h (Aug 6, 2020)

molly 2 said:


> Absolutely  correct , that is why  I run my van  at the plated  tyre pressure  ,  that is the correct  pressure .


When they screwed that plate onto your van, they were very clever to be able to tell exactly what the load on each axle would be, when you are travelling in it.
Can you look to see if next week's lottery numbers are there too?


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## in h (Aug 6, 2020)

Herman said:


> carry a copy of the email as proof.


Have you ever been stopped and had your tyre pressures checked? 
Has anyone you know? 
Has anyone you don't know? 
Has anyone at all?


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## Canalsman (Aug 6, 2020)

molly 2 said:


> Absolutely  correct , that is why  I run my van  at the plated  tyre pressure  ,  that is the correct  pressure .



These pressures are often those attached to the chassis cab before conversion. In that event they relate to usage as a commercial van rather than as a motorhome.


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## mark61 (Aug 6, 2020)

in h said:


> Have you ever been stopped and had your tyre pressures checked?
> Has anyone you know?
> Has anyone you don't know?
> Has anyone at all?



No. 
No.
Don't know.
No idea.
 

Never even been stopped even when my tyre pressures have been very low, but then I don't hammer down a motorway when my tyres are at 1bar.


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## molly 2 (Aug 7, 2020)

Canalsman said:


> These pressures are often those attached to the chassis cab before conversion. In that event they relate to usage as a commercial van rather than as a motorhome.


My van has camper tyres fitted from  new  plateed at 5,0 bar front     ,5 5  rear   ,that is higher than  a fully .loaded  boxer van


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## Millie Master (Aug 7, 2020)

in h said:


> Have you ever been stopped and had your tyre pressures checked?
> Has anyone you know?
> Has anyone you don't know?
> Has anyone at all?



Yes, I have seen the DVSA doing road side checks at their testing station alongside the A52 to the East of Grantham as well as at a similar location to the West of Sleaford alongside the A17 and I have read on several Facebook motorhoming groups as well as another forum of similar road side tests, so it might be better not trying to be a smart ass!


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## Tookey (Aug 7, 2020)

in h said:


> Have you ever been stopped and had your tyre pressures checked?
> Has anyone you know?
> Has anyone you don't know?
> Has anyone at all?


It's a peice of paper, why would you not. You carry a warning triangle, a spare tyre, fire extinguisher etc with the hope you never use them so I don't see why this is any different.

It takes up no space, adds no weight and might prevent a load of hassle (especially if abroad), no brainer as far as I'm concerned and will follow the advice when I get new tyres.


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## in h (Aug 7, 2020)

Tookey said:


> It's a peice of paper, why would you not. You carry a warning triangle, a spare tyre, fire extinguisher etc with the hope you never use them so I don't see why this is any different.
> 
> It takes up no space, adds no weight and might prevent a load of hassle (especially if abroad), no brainer as far as I'm concerned and will follow the advice when I get new tyres.


The difference is that the warning triangle and fire extinguisher are legal requirements in some places. The spare tyre is of use to me.


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## in h (Aug 7, 2020)

Millie Master said:


> Yes, I have seen the DVSA doing road side checks at their testing station alongside the A52 to the East of Grantham as well as at a similar location to the West of Sleaford alongside the A17 and I have read on several Facebook motorhoming groups as well as another forum of similar road side tests, so it might be better not trying to be a smart ass!


I have seen DVSA doing vehicle checks. That's not to say that they were checking tyre pressures. 
Because I have read it on Facebook does not make it a reality.


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## Tookey (Aug 7, 2020)

in h said:


> The difference is that the warning triangle and fire extinguisher are legal requirements in some places. The spare tyre is of use to me.


Fair points


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## Canalsman (Aug 7, 2020)

molly 2 said:


> My van has camper tyres fitted from  new  plateed at 5,0 bar front     ,5 5  rear   ,that is higher than  a fully .loaded  boxer van



Those pressures sound way too high in my view.

The camper tyres will have been fitted by the converter in place of the van tyres fitted when the base vehicle left the factory.


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## in h (Aug 7, 2020)

It's easy for anyone to establish the correct tyre pressures for themselves, by loading up FULLY and going to a weighbridge (complete with passengers and pet dog/gerbil/hippo). 
From the individual axle weights, it is easy to calculate the correct pressures.
Without that information, it is impossible; so the maker and the converter and the tyre company understandably play safe and suggest the highest possible pressure, with a bit extra added for a safety margin. And everything rattles, the handling is terrible and the tyres wear in the middle.


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## in h (Aug 7, 2020)

Tookey said:


> It's a peice of paper, why would you not.


Indeed, it is worth slightly less than the paper it is written on. 
If you like, I can send you an email from God, or from the tyre manufacturer of your choice, that says your tyres should all be at exactly 17.25psi.
And if you were to be stopped by VOSA and had your vehicle checked over, how much notice do you think a trained vehicle examiner would take of a bit of paper? They know that the correct pressure depends on the load, not on a bit of paper, or, indeed, on a plate screwed to the vehicle.


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## in h (Aug 7, 2020)

mark61 said:


> With so many people using TPMS's, would be interesting to see views on the old 4/6 PSI rule.


I've no idea what the 4/6 psi rule is, but for four and sixpence, you could probably buy one shot at a garage tyre pump.
I puffed my car tyres up yesterday morning, before it went for its MOT at lunchtime.
The TPMS told me that the tyres were at 31psi all round. 
I had to do a trip out today, doing about 70 miles, mostly on motorway. It has been a hot day. 
The temperatures rose to 34, 34, 35 and 37 degrees, the pressures rose to 33, 33, 35 and 36 psi
Make what you will of that: I don't usually take that much notice, but I wanted to know if one has a leak.


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## Nabsim (Aug 7, 2020)

Am I the only person who runs their tyres nitrogen filled? Does away with the temperature variances


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## in h (Aug 7, 2020)

Nabsim said:


> Am I the only person who runs their tyres nitrogen filled? Does away with the temperature variances


My tyre pump seems to use normal air, so they are 78% nitrogen-filled. 
Pressure variations with temperature are not a problem as far as I can see.


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## Nabsim (Aug 7, 2020)

Tyre place will top mine up for free but now I have moved they will start to get air added as needed. You can get them refilled though but no idea on costs


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## Tookey (Aug 7, 2020)

in h said:


> It's easy for anyone to establish the correct tyre pressures for themselves, by loading up FULLY and going to a weighbridge (complete with passengers and pet dog/gerbil/hippo).
> From the individual axle weights, it is easy to calculate the correct pressures.
> Without that information, it is impossible; so the maker and the converter and the tyre company understandably play safe and suggest the highest possible pressure, with a bit extra added for a safety margin. And everything rattles, the handling is terrible and the tyres wear in the middle.


ok, I get the maths bit, where I am still a bit lost is how it takes into account the actual tyre and the variables that come into play with different makes/models


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## molly 2 (Aug 7, 2020)

Canalsman said:


> Those pressures sound way too high in my view.
> 
> The camper tyres will have been fitted by the converter in place of the van tyres fitted when the base vehicle left the factory.


In my view and  the view  of the motorhome manufacture that is the correct  pressure


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## mark61 (Aug 7, 2020)

in h said:


> I've no idea what the 4/6 psi rule is, but for four and sixpence, you could probably buy one shot at a garage tyre pump.
> I puffed my car tyres up yesterday morning, before it went for its MOT at lunchtime.
> The TPMS told me that the tyres were at 31psi all round.
> I had to do a trip out today, doing about 70 miles, mostly on motorway. It has been a hot day.
> ...



Well, I guess if you average out your rise in psi, your roughly at 4 psi, good enough to prove the rule   

The 4/6 psi rule has been around for years. Some people even go so far as say that's how manufacturers work out psi for loads. 
Strangely, although theres a lot of stuff about the rule online, Coopers appear to be the only manufacturer to mention it, or the only one I've seen.

I've never taken too much notice of the rule, apart from notice that on good tarmac it seems to be pretty close to what TPMS show. The rougher the roads, the more "out the window it goes"

No where near as accurate as working out psi by going to weigh bridge and working from load rating, but probably more accurate than pumping up to full psi because thats what the plate say.


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## mark61 (Aug 7, 2020)

Tookey said:


> ok, I get the maths bit, where I am still a bit lost is how it takes into account the actual tyre and the variables that come into play with different makes/models


 Because the load rating of the tyre is part of the calculation.


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## mark61 (Aug 7, 2020)

molly 2 said:


> In my view and  the view  of the motorhome manufacture that is the correct  pressure


 They have no idea if your van is empty or fully loaded.


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## in h (Aug 7, 2020)

molly 2 said:


> In my view and  the view  of the motorhome manufacture that is the correct  pressure


Yes, but in the view of someone who had the facts at their disposal, you would get a very different number.


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## in h (Aug 7, 2020)

Tookey said:


> ok, I get the maths bit, where I am still a bit lost is how it takes into account the actual tyre and the variables that come into play with different makes/models


The actual tyre has its individual load rating printed (in code) on the sidewall. It also has the pressure recommended for that load printed on the sidewall.


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## molly 2 (Aug 7, 2020)

Nabsim said:


> Am I the only person who runs their tyres nitrogen filled? Does away with the temperature variances


Proberbly not  ,I was told by a director  of a major tyre company it is just a money maker  driven by boy racers that like to think they racing  drivers


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## in h (Aug 7, 2020)

mark61 said:


> Well, I guess if you average out your rise in psi, your roughly at 4 psi, good enough to prove the rule.


Guess so, but the car has a plate giving the recommended pressures. 
The recommended pressures for the tyres are in a complicated table showing load, speed and pressure. The recommended rear pressures vary (from memory) between 31psi and 47psi. The front pressures from 29psi to something in the mid 30s.
The table makes no mention of temperature differences.


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## molly 2 (Aug 7, 2020)

in h said:


> Yes, but in the view of someone who had the facts at their disposal, you would get a very different number.


If you bought  a lambo would you use manufactures pressure  or something from a web site ?


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## in h (Aug 7, 2020)

molly 2 said:


> If you bought  a lambo would you use manufactures pressure  or something from a web site ?


Of course not, my engineering team would work the correct pressure.


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## Canalsman (Aug 7, 2020)

The point that we're all making is that to achieve the best comfort, and best tyre life, the pressures must be in accordance with the vehicle loading.

The correct pressures can be calculated yourself based on the weighbridge values or provided to the tyre manufacturer for advice.

Most cars, especially estates, have tyre pressures detailed in the handbook based on vehicle loading. Motorhome converters don't seem to provide this guidance.


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## mark61 (Aug 7, 2020)

Nabsim said:


> Am I the only person who runs their tyres nitrogen filled? Does away with the temperature variances


 
Not for my van. On some trips I can be messing with pressures daily.
If I had built in inflation system it would be more, but I haven't.


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## Nabsim (Aug 7, 2020)

molly 2 said:


> Proberbly not  ,I was told by a director  of a major tyre company it is just a money maker  driven by boy racers that like to think they racing  drivers


On one of the coating plants we would get truck exploding due to the heat Baz. Michelin advised us to use nitrogen and the problem went away. If we had a power failure and the process stopped the drums would melt the tread on the tyres depending what we were mixing, much more heat than British weather that’s for sure.
When I had a new set of tyres fitted nitrogen fill was part of the service free. For anyone concerned about pressure changes with temperature I would say use nitrogen.
Now I have moved away I will gradually revert to good old air though, a little drift doesn’t bother me


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## Nabsim (Aug 7, 2020)

mark61 said:


> Not for my van. On some trips I can be messing with pressures daily.
> If I had built in inflation system it would be more, but I haven't.


I hadn’t had to touch mine for about 14 months so didn’t affect me. I wouldn’t go to onboard nitrogen tank unless I was drag racing lol


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## molly 2 (Aug 7, 2020)

Very true tp    do increase with  heat  that is why tp should be checked when cold and not adjusted when hot


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## molly 2 (Aug 7, 2020)

Nabsim said:


> On one of the coating plants we would get truck exploding due to the heat Baz. Michelin advised us to use nitrogen and the problem went away. If we had a power failure and the process stopped the drums would melt the tread on the tyres depending what we were mixing, much more heat than British weather that’s for sure.
> When I had a new set of tyres fitted nitrogen fill was part of the service free. For anyone concerned about pressure changes with temperature I would say use nitrogen.
> Now I have moved away I will gradually revert to good old air though, a little drift doesn’t bother me


Always had you down as a bit of a drifter  Neil


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## sydnsue (Aug 9, 2020)

The pressures plated in the cab are for the base chassis as a commercial vehicle. It is the manufacturers plate, not the motorhome plate. I'm on a Boxer chassis and like most others, 50 front 60 rear seems perfect. Vanco tyres. These are the pressures most users are receiving from the tyre manufacturer. The weights from one user to another don't vary that much from unladen to laden. We all have to stay within quite a small band.


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## Sid (Aug 12, 2020)

wildebus said:


> Do VOSA actually check Tyre Pressures on a private vehicle?   I can imagine they might be able to see an obviously underinflated tyre, but there is not a "one pressure fits all" tyre pressure to suit all circumstances - it depends very much on the loading of the vehicle and the type of driving.


Very true but there is the ability to check axle loads on moving vehicles, so it's quite straight forward to work out the appropriate pressures accordingly. I do however have no idea what the lea way is.


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## wildebus (Aug 12, 2020)

Sid said:


> Very true but there is the ability to check axle loads on moving vehicles, so it's quite straight forward to work out the appropriate pressures accordingly. I do however have no idea what the lea way is.


Not sure if that would tell you anything? Too many factors with tyre sizes as well.
Over thinking a non-issue


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## Deleted member 80299 (Aug 12, 2020)

Herman said:


> Finally after 3 years of ownership I decided to drop the tyre pressures on the back axle from 70PSI to 65PSI and wow! what a difference to the internal travel noises, the bathroom door being the main one not rattling any more. I'll try dropping the fronts by 5PSI next.
> 
> What pressure do others run their tyres at.


What does your Motorhome maker say the pressures should be? mine(autotrail say 6 bar). If you run at less, does it invalidate your insurance?


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## in h (Aug 12, 2020)

The correct tyre pressure depends on the load. The motorhome maker can only guess at the load you'll out on, so they estimate high. Very high. Too high, usually.
Read your insurance policy if you want to know what affects it: that defines the conditions, not something you read on the web.


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## Tookey (Aug 13, 2020)

in h said:


> The correct tyre pressure depends on the load. The motorhome maker can only guess at the load you'll out on, so they estimate high. Very high. Too high, usually.
> Read your insurance policy if you want to know what affects it: that defines the conditions, not something you read on the web.


In h,

You seem to be very knowledgeable and quite interested in this subject. Although it seems very straightforward to you, to others, myself included, it is a tad confusing. If you can be bothered to do a guide to tyre pressures, requirements and relevant calculations it would be an asset to the forum. ( vehicle manufacturer guidelines, tyre manufacturers guidelines, own weight calculations )

Just a thought as there is some good info in this thread but it's now all jumbled up and not very user friendly and I didn't find anything online that covered all aspects of such a crucial area. I do appreciate we are all busy people


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## Okta (Aug 13, 2020)

Canalsman said:


> The point that we're all making is that to achieve the best comfort, and best tyre life, the pressures must be in accordance with the vehicle loading.
> 
> The correct pressures can be calculated yourself based on the weighbridge values or provided to the tyre manufacturer for advice.
> 
> Most cars, especially estates, have tyre pressures detailed in the handbook based on vehicle loading. Motorhome converters don't seem to provide this guidance.


My Carthago hand book gives a full range of pressures for various axle weights and tyres.


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## Deleted member 47296 (Aug 13, 2020)

In the past when I looked into the question of which guidance is legal I have been told that in effect you are safe to follow the guidance of those who should know best. That means if you follow either the tyre manufacturers guidance, the vehicle manufacturers guidance or any other respected authority such as TyreSafe you cannot be seen to have been negligent. Basically if you can show that you didn’t make it up as you went along you are ok.


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## Sid (Aug 13, 2020)

Nabsim said:


> Am I the only person who runs their tyres nitrogen filled? Does away with the temperature variances


As far as I am aware Charles and Boyles law apply equally to nitrogen as to air, what using nitrogen does for you is reduce the water vapour so less corrosion.


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## Nabsim (Aug 13, 2020)

Sid said:


> As far as I am aware Charles and Boyles law apply equally to nitrogen as to air, what using nitrogen does for you is reduce the water vapour so less corrosion.


So what stopped exploding tyres at high temperatures then?


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## Nabsim (Aug 13, 2020)

Sorry yes, nitrogen will reduce the tyre temperature under load (or high speeds) it will also slow down passing through the carcass. And isn’t affected the same by cold temperatures (that’s the water bit maybe?)

How could I think any of the above may have bearings on tyre pressures


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## wildebus (Aug 13, 2020)

Sid said:


> As far as I am aware Charles and Boyles law apply equally to nitrogen as to air, what using nitrogen does for you is reduce the water vapour so less corrosion.


I thought the idea of using Nitrogen was to give less variance as the tyre warms up  (this I think is how it is promoted by Costco at least I think?), so  after reading the comment above, I did a little search on the Internet for some info and calculators ....

Found this calculator for Nitrogen - https://icemeister.net/backroom/calculators-2/nitrogen-pressure-vs-temperature-calculator
And this one for "air" - http://physics.bu.edu/~schmaltz/deflate.html . Calc references a Football, so will guess it is based on normal everyday air rather than any exotic gases

On the assumption that both calculators are correct, using Nitrogen actually makes no difference whatsoever in terms of Pressure Variation!


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## Nabsim (Aug 13, 2020)

I posted directly above you Dave, it’s the speed and load but that does it not ambient. I had to have a check as I knew it cured a biggish problem we used to suffer.


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## wildebus (Aug 13, 2020)

Nabsim said:


> I posted directly above you Dave, it’s the speed and load but that does it not ambient. I had to have a check as I knew it cured a biggish problem we used to suffer.


I just read your reply after I posted mine.
So Nitrogen changes pressure as temp increases in the same way as air, BUT .... using nitrogen actually stops the temp variation to such a degree that the end result is a more even temperature and therefore a more even pressure in the tyre.  Is that correct?


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## Nabsim (Aug 13, 2020)

wildebus said:


> I just read your reply after I posted mine.
> So Nitrogen changes pressure as temp increases in the same way as air, BUT .... using nitrogen actually stops the temp variation to such a degree that the end result is a more even temperature and therefore a more even pressure in the tyre.  Is that correct?


That’s the way I took it. I wouldn’t have paid any extra to get the van filled with nitrogen it was a freebie I didn’t even know about until I got the invoice. I do know it stopped the truck tyres exploding on a drum used for heating stone to temperature for producing asphalt. There would be more heat in the tyre than on a van in the uk I would think as the tread got shiney while in use, bit like you see F1 tyres when heat blanket removed.


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## in h (Aug 13, 2020)

Tookey said:


> Just a thought as there is some good info in this thread but it's now all jumbled up


The problem is that it is a discussion forum. People like to assert and reassert what they've been told. Even when it was wrong or misunderstood. And that's their right.
Until recently, the BBC used to always include a climate change denier in any discussion in the interests of "balance". (though never a representative of the Flat Earth Society when discussing anything to do with space).
A reference site where you get reliable information you can depend on doesn't sit comfortably on a discussion forum


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## Nabsim (Aug 13, 2020)

There is a documents area on motorhomebuilder for info. In the case of tyres I prefer to use what Conti told me to anything else. From what I have seen posted around though other manufacturers may not give you ‘your’ info.


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## Tookey (Aug 13, 2020)

Considering correct tyre pressures are so important from a legal, safety and environmental point I was disappointed to find nothing on the DVLA site.....unless I missed it. Will look around the net and motorhome builder


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## mark61 (Aug 13, 2020)

No one expects delivery drivers to adjust their pressure between loads, and the "correct" pressure can vary hugely between empty and full loaded. The correct or maybe recommended pressure could well be 45psi empty and 70+psi laden, these drivers aren't braking the law by running at 70psi empty, but probably would be if running at 45 psi fully laden.

So you have to work out tyre pressures yourself, knowing weights and tyre specs. Then you may also want to take other things into account, ie. If doing a fast drive down to the Pyrenness, toll roads or fast roads all the way, I'll choose a different pressure than I would if trundling around Poland, where I'll go for softish tyre anyday, but I also know I won't be doing motorway speeds, which in France is much faster than here


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## Nabsim (Aug 13, 2020)

I use the loaded settings Conti gave me but I don’t load and unload so I doubt it would be much out. In a Moho most wont have more than 300kg difference I expect.


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## Sid (Aug 13, 2020)

wildebus said:


> I thought the idea of using Nitrogen was to give less variance as the tyre warms up  (this I think is how it is promoted by Costco at least I think?), so  after reading the comment above, I did a little search on the Internet for some info and calculators ....
> 
> Found this calculator for Nitrogen - https://icemeister.net/backroom/calculators-2/nitrogen-pressure-vs-temperature-calculator
> And this one for "air" - http://physics.bu.edu/~schmaltz/deflate.html . Calc references a Football, so will guess it is based on normal everyday air rather than any exotic gases
> ...


I think the big difference is that the nitrogen from a cylinder will be dry, whereas the air will have a significant amount of water included which will make a afir difference if it turns to a vapour, which maybe what was happening in Nabsim's example. I doubt many garages fit a dryer in line on their compressors. So go with your plan of sticking with Conti's pressures.


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## wildebus (Aug 13, 2020)

Sid said:


> I think the big difference is that the nitrogen from a cylinder will be dry, whereas the air will have a significant amount of water included which will make a afir difference if it turns to a vapour, which maybe what was happening in Nabsim's example. I doubt many garages fit a dryer in line on their compressors. So go with your plan of sticking with Conti's pressures.


just to say .... not MY plan  (I don't agree with the idea of blindly pumping to whatever the maximum pressure quoted is)


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