Tyres in high temperatures. Help! (1 Viewer)

May 12, 2016
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Any thoughts would be greatly appreciated. On our way down near Valencia we had the frightening experience of a tyre shredding. Put new spare on. Must be said tyre that shred had been on van since we bought it about 4yesrs ago, so how old it was we don't know but appeared ok when checked. We bought a new camper tyre and replaced other rear wheel(now spare)
While in Morocco temps around 30°+ my husband feels both rear tyres look soft yet the pressure is 70 psi are new camper tyres. We are not loaded as much as we have been on other trips. Is it possible that this is normal due to van weight (4 ton) high temps etc and his bad experience of the tyre shredding.
Help please
.
 

Flamenca

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The first question that pops into my head is what was the load index of the old tyres compared to the maximum axle weight?
 

funflair

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You should be able to find a date code on your tyres and the norm is to change them between 5 and 7 years, the temperature should not affect how the tyre looks.

Martin

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Badknee

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The plate on ours tells us 5.5 bar is ok for the rears, that's more than 70psi which I run ours at.
 

funflair

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The first question that pops into my head is what was the load index of the old tyres compared to the maximum axle weight?
Good point(y) that will be on the tyre as well it should follow the tyre size.

Martin

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mikebeaches

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I've got a tyrepal pressure monitor on the van that also shows the individual tyre temperatures. And it is surprising how hot they can become when motorway driving, somewhere like the Med in summer. Also, the pressures increase significantly because of the heat. Even to the extent it set off the alarm on one occasion - but that was because I hadn't appreciated how big the difference would be and, consequently, hadn't allowed sufficient pressure or temperature tolerance when setting up the system.

But provided the tyres are in good condition and the correct pressure, it shouldn't cause any problem at all.
 
Nov 23, 2011
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If the tyres are only 70 psi in those temperatures and look 'soft' then I would suggest they are under inflated. Do what's been suggested and inflate the rear tyres to 5.5 bar ( 80psi).

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dabhand

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Went through six in Portugal last year, if I'm honest I did hit a couple of kerbs and several deep potholes. Main causes of tyres shredding would I would think be overloading, over inflation, under inflation, potholes and kerbs with the odd un-noticed raised crossing hit at too fast a pace, take your pick!:((y)
 

Lenny HB

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When are you checking the pressure? If you have been driving you should leave the van standing for 30-60 mintues before checking the pressurer all tyre pressure figures are given for cold tyres.
If you have been checking them after driving they will be underinflated as the pressure will read high.
 

JeanLuc

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An old tyre is a likely cause of the original tyre shredding but assuming you set the tyre pressures before leaving the UK, did you adjust the pressures as you travelled south? If you set the pressures at an ambient UK temperature of 18ºC then travel south into 30º+ then you need to lower the pressures during the trip. I suggest you always check pressures in the morning before travelling.
 
OP
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H
May 12, 2016
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Thanks for all your help it has helped enormously. Conclusion fronts are newish Continental. New one fitted in Spain does not have capacity to increase pressure. Opp tyre can go to 80 psi. So conclusion to keep Spanish new one as a spare and fit a new one to match other new rear tyre 80 psi.

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Lenny HB

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Thanks for all your help it has helped enormously. Conclusion fronts are newish Continental. New one fitted in Spain does not have capacity to increase pressure. Opp tyre can go to 80 psi. So conclusion to keep Spanish new one as a spare and fit a new one to match other new rear tyre 80 psi.
The max pressure marked on the sidewall is only for the American market. Don't normally run Continental's at that pressure only Michelin Camping tyres. it's always adviable to have matching tyres on the same axle.
 
Oct 2, 2008
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If you are running at load close to max load marked on tyre then you will see the max load pressure also marked on the tyre . You should set this pressure with tyre cold , eg in morning with almost no travel . Under no circumstances should you check the tyre pressure after a run and then bleed air off . Heat is the biggest killer of tyres both quickly and slowly ( mileage usability) . Pressure rise thru heating is factored into tyre manufacturers recommended pressures . I lived and sold tyres in Australia for a good few years and we had a system for inflation pressure adjustment Inflate tyre to
recommended , when cold , after driving check pressure if more than 4psi rise then tyre was underinflated to start, if less than 4psi then overinflated only works for same load , but gives best ride / mileage , but is rather fiddly .
Continental have a tech advice and pressure chart site https://www.continental-tyres.co.uk/car/technology/tyre-knowledge/tirelexicon-3-0/tirelexikon-3-1
 

funflair

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If you are running at load close to max load marked on tyre then you will see the max load pressure also marked on the tyre . You should set this pressure with tyre cold , eg in morning with almost no travel . Under no circumstances should you check the tyre pressure after a run and then bleed air off . Heat is the biggest killer of tyres both quickly and slowly ( mileage usability) . Pressure rise thru heating is factored into tyre manufacturers recommended pressures . I lived and sold tyres in Australia for a good few years and we had a system for inflation pressure adjustment Inflate tyre to
recommended , when cold , after driving check pressure if more than 4psi rise then tyre was underinflated to start, if less than 4psi then overinflated only works for same load , but gives best ride / mileage , but is rather fiddly .
Thats interesting, I dont know how many on here with Tyre Pal see less than 4psi increase, I know I see close on 10psi within 10 miles and then no more (60 to 70)

Martin

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JeanLuc

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Also, if you are running at high pressures, make sure the supplier fitted a metal stemmed valve that is designed to cope. The standard Schrader tyre valve is designed for a maximum of 4.5 bar / 65psi
 
Feb 9, 2008
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For correct Tyre pressure you need to weigh your van, then give the axle weights and tyre details to the tyre manufacturer who will tell you what tyre pressure you need. I produced this table below from their technical guide and will see if I can find it and get it on here as your sizes will no doubt be different.


Tyre Pressures and Axle weights for Continental Vanco Camper tyres 215/70R 15CP 8PR 109
Agreed by Continetal Technical Staff.
Bar 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50

Front Axle 1425 1520 1615 1705 1795 1885 1975 2060

Rear Axle 1270 1350 1435 1516 1595 1675 1755 1830 1910 1985 2060
 
Feb 9, 2008
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Here you go. Hope this helps.

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DBK

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If you are running at load close to max load marked on tyre then you will see the max load pressure also marked on the tyre . You should set this pressure with tyre cold , eg in morning with almost no travel . Under no circumstances should you check the tyre pressure after a run and then bleed air off . Heat is the biggest killer of tyres both quickly and slowly ( mileage usability) . Pressure rise thru heating is factored into tyre manufacturers recommended pressures . I lived and sold tyres in Australia for a good few years and we had a system for inflation pressure adjustment Inflate tyre to
recommended , when cold , after driving check pressure if more than 4psi rise then tyre was underinflated to start, if less than 4psi then overinflated only works for same load , but gives best ride / mileage , but is rather fiddly .
Continental have a tech advice and pressure chart site https://www.continental-tyres.co.uk/car/technology/tyre-knowledge/tirelexicon-3-0/tirelexikon-3-1
From that link you can download the document for vans and 4*4s.

You need to find in there your tyres, for example, we have 225/R16C which are on page 82. Then on page 83 you find the recommended pressure for that tyre based on axle loading - you need to print out both pages for convenience. Of course you can only find your axle loading using a weighbridge which probably isn't much help if you are in Morocco. :)

But if you have the axle loading you can find the recommended pressures for your tyres which are probably a lot lower than you might expect.

This only applies to Continental tyres of course. :)
 

Badknee

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We're running on "light truck" tyres. I started off with 60psi front and 55psi rears (tag). Now we have the scoot on the rack I'm up to 65psi front and 70psi rears. The ride is harsher but the tyres look ok.
 
Oct 2, 2008
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We're running on "light truck" tyres. I started off with 60psi front and 55psi rears (tag). Now we have the scoot on the rack I'm up to 65psi front and 70psi rears. The ride is harsher but the tyres look ok.
You want to reweigh and you might be able to lower the front pressures as the scoot will lighten the front axle transferring the weight to more on rear , this would give you a better ride on front with no detriment to front tyres ;)
 

joka250

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If the tyres are only 70 psi in those temperatures and look 'soft' then I would suggest they are under inflated. Do what's been suggested and inflate the rear tyres to 5.5 bar ( 80psi).
If they look soft temperature has little or nothing to do with it. They are more likely overloaded or degraded.
 
OP
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May 12, 2016
141
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Blackwood Caerphilly
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N&B Arto
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Since 1986
Latest is we cannot find a 75 or 80 psi tyre in Maroc. Been to few, one is Liberty who have a number of sites. They have rung around and nothing over 70 psi.
Unless someone out there knows different.

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Dec 23, 2014
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I suspect that your tyres are on their last legs age wise. That said tyre pressures should always be checked when cold and when if set correctly the running temperature should not rise massively in use. After a run in UK ambient temperatures I check mine by touch. If I can comfortably hold my hand on each tyre then I consider the pressure okay; too hot indicates pressure to low, too cold pressure too high. In hot countries / conditions you should always increase the pressures to reduce wall flexing and heat build up. Adding 10 psi is not out of the question.
 
OP
OP
H
May 12, 2016
141
49
Blackwood Caerphilly
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N&B Arto
Exp
Since 1986
I suspect that your tyres are on their last legs age wise. That said tyre pressures should always be checked when cold and when if set correctly the running temperature should not rise massively in use. After a run in UK ambient temperatures I check mine by touch. If I can comfortably hold my hand on each tyre then I consider the pressure okay; too hot indicates pressure to low, too cold pressure too high. In hot countries / conditions you should always increase the pressures to reduce wall flexing and heat build up. Adding 10 psi is not out of the question.
Thanks Dorset Diver but I did say that current tyres are brand new on rear and about 9 months on front.
 
Feb 9, 2008
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After a run in UK ambient temperatures I check mine by touch. If I can comfortably hold my hand on each tyre then I consider the pressure okay; too hot indicates pressure to low, too cold pressure too high. In hot countries / conditions you should always increase the pressures to reduce wall flexing and heat build up. Adding 10 psi is not out of the question.
I find your statement surprising to say the least. There is no logic what-so-ever to this method and you may well be placing yourself and others in harms way. Use a calibrated tyre gauge when the tyres are cold to establish your true tyre pressure.

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