Tyre pressure too high?
I have a Hymercar and find the ride quality is quite harsh so have been doing some research online, one of the things people talk about is having the tyre pressure too high.
I haven’t weighed my van yet but the Hymer manual says the tyre pressure should be 3.75 bar on the Front and 4.3 bar on the rear. I have contacted the tyre manufacturer and they have provided me tyre chart. This show that a front tyre pressure of 3.75 bar would be required for a front axle load of circa 1965 kg and a rear tyre pressure of 4.3 bar would be required for a rear axle load of circa 2170 kg.
However, even my vans max axle weights (front axle max of 1850kg and a rear axle max 2000kg) are way below this.
So my question is should I take my van to a weighbridge and once I have the actual weights reduce my tyre pressure accordingly?
Thanks for any advice.
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Or just experiment.
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The pressures don't sound particularly high, in old money approx 54 and 62 PSI? You could have a look here https://www.tyresafe.org/motorhome-tyre-safety/ where they have charts for certain weights. Obviously you would need to establish the actual weights by using a weighbridge.
David
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Don't experiment, that could be dangerous. Put your van into travelling trim, i.e. with everything you would normally carry including passenger(s), about 90% fuel and your normal amount of fresh water. Get it weighed, total and both axles. Armed with that info ask your tyre manufacturer to recommend pressures. Michelin and Goodyear are very helpful and I assume that others will be equally good.
PS What make, size, and type (model) of tyres are fitted?
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I agree, and apologise for possibly misleading people. Experimentation should only be tried by those who have a good working knowledge of what they're about.
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Sound advice. Advice should only be offered by people with a good working knowledge of what they’re talking about.
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It’s so easy to assume that others have the same level of understanding as one's self.
Similarly, it’s easy to misunderstand the subject of a thread as you well know.
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I am able to calculate a pressure for you.
Made spreadsheets for motorhomes and caravans.
Do it yourselfes methode is first ad 10% reserve to the determined axleload. And calc lineair.
If you give tyres maxload and " max pressure, I will do it for you.
https://1drv.ms/f/s!AtzmkuDu4Calhhn9AlpqWau-PjbR
In this map the motorhome calculator and the map for traveltrailers. This map is also for America, thats why tire instead of tyre. But you can select the English language.
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an old fashioned way of checking tyre pressures-
get some chalk and cover the tread in a band of about 2-3" wide 90 degrees to the sidewall, go for a short drive.
check the chalk band,
if it is worn in the middle = overinflated
if it is worn on the edges = underinflated
if the band is worn evenly across the tread = perfect
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This comes up regularly and is an issue for many motorhomes. If you can find a public weighbridge then they will write down front and rear axle weights for free although if you want a ticket you have to pay. Use manufacturers’ tyre data.
My front tyres were way too high and the ride has been transformed by reducing the pressure down to the values quoted by Continental. Unfortunately, for Peugeot (Autosleepers), the weights stamped inside the near side door column are the base vehicle not the converted coachbuilt so are too high. Can’t reset the warning signal though which is another big issue.
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I had that issue with my Marquis. Experimented to find the lowest I could go without the warning appearing every time I switched the ignition on.
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A Motorhome is almost always loaded to the maximum allowed, or even over that.
So the list JVB66 has is most likely for the base vehicle.
Rear axle is often overloaded in combination with unequall load R/L, so needs often higher pressure then written on sidewall, because tyres are mostly yust enaugh to cover the Max Permissable Axle Weight( MPAW) .
Front though stays below MPAW , even when overloaded, so can do with much lower pressure.
Only busconversions often use MPAW front fully, because they have shorter overhang behind rear axle.
So my endconclusion is that you most likely have to use the advice given on plate in the motorhome, because that is determined for MPAW's, behind even higher.
Be verry carefull with going lower in the pressures.
A radial tyre stays within a large range with total treath-with on the ground, so even when chalk wears of evenly, you can still have overheated tyres. Only once overheated, beginning crackes are made, wich teare further in time by the normal mechanical forces, whatever you do after that. Then mayby only after 3 years that far, that tyre blows, or treath seperates, and then that once conditions in wich tyre overheated , is long forgotten, and cheap tyres are blamed.
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Forgive me if I misunderstand, my technical English is not strong.
But coachbuilt /panel van conversions is that the usual buildup wit wood and alloy plate on outside?
If so , that is what I mean with the normal motorhome and not busconversion with metall all around.
And for those in general rear higer pressure then max on tyre, wich is not allowed anymore, on CP tyres they give higher pressure.
But front often can do with 4 bar/ 60 psi , sometimes even as low as 3 bar/44 psi. But first let me calculate it for you
Then better comfort, because driver and co-driver are seated close to the front axle, and better gripp, wich is usefull for braking, wich is most on frontwheels.
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Pics show 1) typical coachbuilt motorhome and 2) a typical panel van conversion.
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Then I understood right.
The coachbuild has a much larger overhang behind then the pannel van conversion. This gives much weight on rear axle and low on front. For the pannelvan conversion , weight division front/rear, is more equall, so needed pressure too.
Once determined that the coachbuild has total gravitypoint ( better line) about 41 to 44% of total length from front. The pannelvanconv 45 to 48% because of the metal body wich is more heavy.
But because rear axle is more to the back relatively, the weightdivision over the axles is more equall.
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Temperature in my car is a bit high. ShouldI turn it down? Or ask for advice on a forum? Help for the helpless.
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Happy to provide requested advice. First take the motorhome to a certified laboratory to check the actual temperature in the motorhome over a range of ambients. Next get appropriate graphs from the temperature gauge manufacturer to determine accuracy of the instrument. Finally, work out the difference between the observed temperature and what the gauge is telling you. Armed with that information, if it’s too hot inside then turn it down.
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After you read my posts, you can conclude yourselfes that front 1850kg + 10% = 2035kg, and rear 2000+10% = 2200 kg, yust need those pressures. In my spreadsheet , in case of only MPAW given , I add front 5% because seldom overloaded, and rear 18% to cover most likely overloading.
So search back in your list next.
Front 1850+5%= 1942.5 kg.
Rear 2000+ 18% or 2000/0.9 = 2222kg
Calculated back that you tyres have maxload of 1030 kg is loadindex 109.
Filled that in in my calculator, wich uses formula that gives higher pressure then the officially used, came to 4.3 bar front , and 5.2 bar rear.
5.2 is not allowed on your 8 plyrated tyres, or they must be CP tyres, but to laws of nature it is best to use that 5.2, as long as you did not weigh.
If you give length and wheelbase of your motorhome, I can determine a more realistic weightdivision F/R, and give advice for that.
Advice is for cold measured, this is when temp in and outside the tyre is the same, so when not driven long enaugh and no external factors like sunshine on tyre.
Advice is determined for outside temp of 18 degrC( some write up to 21 degr C.
So extreme hot outside you have to fill higher pressure, so dont blead down, if you measure that higher cold pressure on a hot day.
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As has been said, take the motorhome to a weighbridge when fully laden including driver and passenger(s), fuel, water and all consumables and write down front and rear axle weights. For sure, there may be a small imbalance between offside and near side so a 5-10% allowance can be added to the weights. Check the tyre manufacturer’s data sheets and inflate when cold. Not difficult.
Continental Vanco tyres are very popular and if you have these you should ignore the maximum inflation pressure embossed on the tyre as it’s for the american market and irrelevant in the UK.
Having tried unsuccessfully to get the pressure monitor reset at a Peugeot garage (not main dealer) I just live with the low pressure warning. It has been said on other forums that main dealers will not recalibrate the pressures to lower values than those printed on the door pillar.
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If you have Continental or of that group, you find 2 pressures on sidewall , 1 direct behind the 109/107 Q 65psi.
And on thevother side of sidewall ( 6 o clock) 10 psi higher " maximum inflation pressure"
The 65 psi is then the reference pressure cold , and the 75 psi is the maximum allowed cold pressure.
So then Continental allows you the 5.2 bar behind.
Other brands in C group
Viking , uniroyal, barum, vanco, and some more, and they all give often the 2 pressures.
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Seems like I keep repeating myself. I can’t speak for other makes but for Continental Vanco tyres, Continental tell you to use the pressure charts which correlate to axle loads and ignore what’s stamped on the tyre. Hence you have to go to a weighbridge if you want to reduce the pressures.
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But as long as you did not weigh yet , you have to use pressures on the high side, to prefent once tyre overheats because pressure was to low for the real but unknown weight and speed used.
To high only gives discomfort and bad gripp, but never unsave for the tyres.
Topicstarters advice based on his MPAW's ( F 1850kg, R 2000kg, seached back in list , gives F3.75 , R 4.3 bar.
Asume has the time to weigh and his weights are F 1750kg and R 2200 kg, yes overloaded vehicle and rear axle, but happens often enaugh.
Then its possible that his tires already are damaged by overheating.
And that is what I try to prefent with my advices.
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I actually contacted Peugeot customer service and was told that the pressures could not be changed, I challenged that as Continental had supplied me with a chart which contradicted the Peugeot figures, they changed their minds and told me to contact the Peugeot dealer in Taunton for the recalibration to be done.
For various reasons mainly time and location, I didn’t get it done in the end but still have the communication from Peugeot.
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Probably your Peugeot-dealer will also make it diffucult, and first say its not possible,
Its not that its not possible, but they dont want us users to know better then them.
You have to know who is boss,and if the king says the earth is flat, its flat.
So you have to overwhelm them with facts.
And those are
1. You weighed per axle, or better axle-end, in the loading you go on tripp, so all the persons , freight, water , battery's , gas-bottles, dogs, parrot..... or didn't you?
2. You added 10% to the axleweights for reserve
3. Then looked those weights back in the right pressure-loadcapacity-list for your tyres.
But this shows why they make it that difficult.
Enaugh weigh with not everything in it, and take no reserve. And nowadays they can be held responcible at least partly, when something tyre-related happens.
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I was quoted several hundred pounds when I had my Marquis. I just experimented to find the lowest pressure without triggering the dashboard warning.
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