Tyre Pressures (Again) (1 Viewer)

Peter Ashcroft

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I have a new to us AutoSleeper Windrush 2012 van conversion on a Boxer base, and I am having problems with trying to get the right pressure for the van




After searching this and other forums, the advice on old threads seemed to be weigh vehicle and contact tyre maker.

I have done this (trying to do the right thing) but had no joy and find myself extremely confused and frustrated with the whole thing.

Michelin seemed clueless about it and before I even gave them the weights of axle they said put 80psi in all round, when I explained about the weights they said put 50 front and 80 rear, I asked why the big difference when both axles weighed almost the same, and couldn't get an answer ! the person at michelin both on the phone and on the web chat just didn't fill me with confidence especially when I was given the pressures before he even asked what weight I was running, the feedback from him seemed to be the weight didn't matter and the conclusion was kind of 80PSI in the back no matter what, and put what ever is comfortable in the front...



So I reverted to the tyre safe leaflet here http://www.tyresafe.org/wp-content/uploads/2015/12/motorhome-leaflet.pdf , and even called them, but still I can't get an answer.... so here is my problem!



My tyres are Michelin Agilis Camping tyres, 225-70-15 CP with a 112 load rating. My axle weight is Front 1560KG and Rear 1520KG



The second chart on the leaflet has the pressures for CP tyres, but the lowest weight it starts at is 1952KG front and 1736 Rear which is well above my weight. (for this weight incidentally it states 58 PSI all round, which is well off what Michelin are telling me)



The chart above is for normal commercial tyres, not CP tyres, however on this chart my size and axle weights are listed as they go right down to 1400, for my axle weight in this chart I should be using 40 PSI all round, half of what Michelin are telling me.



I am completely lost, I have no confidence in either of these recommendations now,



If anyone could offer an opinion or advice I would be grateful?

At the moment I am going off the lowest axle weight on the CP tyres chart which is 58 PSI all round, and I must admit the VAN does feel good, however the tyres do look soft when you look at them compared to the old ones. the door card is telling me 59 front and 65 rear which contradicts all of the above.

I might be making too much of an issue of this, but I just want to ensure our vehicle is as safe and as comfortable as I can make it, and I guess I am getting myself all wound up because I have taken the advice so often offered about doing it right and getting the weights etc, and now I have hit a brick wall with it!
 

scottie

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I have same tyres on a 3500kg white van man conversion. Black circles say 79 for the rear 65 for the front. tyre company say 65 rear 60 front. So until I go on a weighbridge, likely to be 72 rear 67 front.
 
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Peter Ashcroft

Peter Ashcroft

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From my experience so far, getting the van weighed hasn't helped :(

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May 8, 2011
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Similar set up and as there is so much debate around it I just put 70 in the back and 60 in the front. It works fine. I have tyre pressure monitors which are well worth the money.
 
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Peter Ashcroft

Peter Ashcroft

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My axles pretty much weigh the same. So are you saying just put what they tell me in the front in the back also ? I will email them though. I have had no luck on the phone. It seems to be a guy called George who answers who is the same guy on the web chat
 
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This is probably the best guide. My rear tyres certainly looked underinflated at the 'recommended' pressure.
 

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Techno

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My axles pretty much weigh the same. So are you saying just put what they tell me in the front in the back also ? I will email them though. I have had no luck on the phone. It seems to be a guy called George who answers who is the same guy on the web chat
It's Michelin policy to quote 80 psi rear regardless
They believe that all Motorhomes are overweight anyway at the back

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premiere99

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I have Toyo HO9's fitted, excellent tyres, especially for Peterborough show this year! and 12 hour response to tyre pressure requests.
When I was at 3500kg I asked them via email.

"I am going to fit 4 x 225/70 R15C 112/110R Toyo HO9 tyres to my Autotrail Cheyenne 635 coachbuilt motorhome. Can you give an indication of tyre pressure for front axle weight of 1680kg and rear axle of 1960kg."

Reply,

"Based on the information you have provided the pressures I would recommend are
Front: 55psi, Rear: 60psi"


After fitting Towbar for the two E-Bikes, VB Air suspension and an "upgrade" to 3850kg by SVTech I enquired again.

"I have 4 x 225/70 R15C 112/110R Toyo HO9 tyres fitted to my Fiat Ducato x250 based Autotrail Cheyenne 635 coachbuilt motorhome.
It has had the suspension uprated with VB-Airsuspension 4C air suspension (front and rear).
Details if required at
Can you give an indication of tyre pressure for front axle weight of 1620kg and rear axle of 2200kg."

Reply

"Based on the information you have provided the pressures I would recommend are
Front: 50psi, Rear: 65psi
I assume that the axle weights given are in a fully laden state, as the rear axle weight is very close to the 2240kg maximum load carrying capacity of the 225/70R15 112/110 tyres.

Best regards
Alan Meaker
Technical and Motorsport Director Toyo Tyre UK"


I cannot see how Michelin can say 80PSI all round and then change that to 50PSI in the front, seems a bit finger in the air to me, glad I have Toyo's and great grip on grass!





 
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Peter Ashcroft

Peter Ashcroft

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Screen Shot 2016-05-27 at 11.43.33.png
Just been sent this My Michelin , still doesn't not help as my axle weight isn't on there and is well below the weights listed
 

Techno

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Pressure is proportional to weight it's only maths

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Techno

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Looks like they don't like to quote below 50 psi but as your rear is lighter than the front I don't see the issue with applying 50 psi all round
 

TerryL

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Just interested, as it's unusual to see the front heavier than the rear on modern vans, what are your "plated" weights, i.e. what does the plate affixed to your van read (be 4 sets of numbers)? Should be in the cab area somewhere, maybe in a footwell. Does the MAUW (third set) agree with your V5?
 
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Peter Ashcroft

Peter Ashcroft

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Glad you're paying attention (y)
29kg per 1 psi

Techno, thanks so much for taking the time to work that out, My head is battered though, could you make it even simpler for me and just tell me what PSI I need based on your calculations and my weights??

Front - 1560KG
Rear - 1520KG
Total - 3080KG

Tyres 225-70-15
 
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Peter Ashcroft

Peter Ashcroft

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Actually thinking about this now, even though the vehicle was loaded ready for a typical outing, I was not in the vehicle when it was weighed and I weight about 100KG so the front really should be 1660 KG!

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Peter Ashcroft

Peter Ashcroft

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My rather brutal reply, but I was really fed up by this point!
Screen Shot 2016-05-27 at 19.42.07.png

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Peter Ashcroft

Peter Ashcroft

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and finally the plate that was asked for... I too find it unusual that the front is heavier!
IMG_0019.jpg

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Techno

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and finally the plate that was asked for... I too find it unusual that the front is heavier! View attachment 108208
Even my front is heavier until I load my bikes and the garage

The front has the engine the diesel and in most cases two people
Mine has water and gas right behind us too
 
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Peter Ashcroft

Peter Ashcroft

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Thanks again for your help, at the moment I am running 58 PSI all round, and the van drives very well, So I think I will stick to whats in it as it is close enough, but at least now I can breathe a little easier knowing I am safe.. I was really worrying I was under inflated, I work away in the van most weeks and it does a lot of motorway miles each week

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