AnnPaul Posted April 3, 2009 Share Posted April 3, 2009 Some time ago I asked Michelin tyres what inflation I should have in my tryes, they in formed me that the my Michelin Camping tyres 215/70 15C , with rear axle weight of 1860 and front 1600 should be rear 60 and front 55. Have been a little concerned about these pressures so have just phoned them again only to be told that the tyres should be rear 80 and front 70 What's gone wrong when you ask they so called "experts" and they give two complete different answers!!!. If it had been just a few lbs I would not have worried but a difference of 20 and 15, what do I do. Will be interested in other comments before I contact Michelin to complain. Paul Link to comment Share on other sites More sharing options...
hymer1942 Posted April 3, 2009 Share Posted April 3, 2009 I e mail Michelin and got the reply 65 front and 62 rear [ twin wheeled ] which I am quite happy with. S Class Hymer Link to comment Share on other sites More sharing options...
AnnPaul Posted April 3, 2009 Author Share Posted April 3, 2009 Have just e-mailed the details of my tryes to Michelin. It will be interesting to see what they come back with. Paul Link to comment Share on other sites More sharing options...
Ranger Posted April 3, 2009 Share Posted April 3, 2009 What is an "EXPERT"??? Ex = "hasbeen"! "Spirt" = Drip under pressure!!! So who can you trust??? Link to comment Share on other sites More sharing options...
Derek Uzzell Posted April 3, 2009 Share Posted April 3, 2009 AnnPaul Based on Michelin's technical handbook, for XC Camping 215/70 R15C tyres and axle weights of 1600kg (front) and 1860kg(rear), the pressures you were previously recommended - 55psi(F) and 60psi® - appear to be appropriate. Link to comment Share on other sites More sharing options...
Guest peter Posted April 4, 2009 Share Posted April 4, 2009 I wouldn't want to be sitting in it on a bumpy road at 80 psi in the rear. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted April 4, 2009 Share Posted April 4, 2009 Paul You have not said what motorhome you own, but I'd guess (based on the tyre size and type) that it's based on a pre-2006 Fiat Ducato/Peugeot Boxer 3500kg chassis. For motorhomes with that chassis fitted with 215/70 R15C XC Camping tyres Fiat's own workshop manual advised tyre inflation pressures of 72.5psi (F & R), Pilote's Owners' Manual advised 72.5psi(F) and 80psi®, while Hobby's User Manual advised 65psi(F) and 80psi®. In Michelin's technical handbook there is also a footnote relating to the XC Camping pattern. This says "For maximum load conditions when used on mainland Europe it is recommended that the rear tyres are inflated to a pressure of 80psi." Obviously I can't know the content of your latest telephone dialogue with Michelin. Was there a misunderstanding about tyre size? Was there 'finger trouble' on the part of the Michelin adviser? Were the data that he/she accessed incorrect? (Don't think that doesn't happen - I could point to data in Michelin's technical handbook that I know, without a shadow of a doubt, are badly wrong.) I'm surprised that, knowing that the 70/80 pressures you'd just been given differed so much from the 55/60 figures Michelin originally provided, you (apparently) didn't challenge the latest recommendations at the time - I'm certain I would have done. I try to avoid seeking technical advice by phone if I can avoid it. It puts the (often anonymous) person at the other end of the phone-line under pressure to provide an immediate answer, which invites a best-guess knee-jerk response. I'd much rather use e-mail. Even then, when I've tried my hardest to define exactly what I want to know and to avoid any possible ambiguity, I've had replies to my e-mails that have left me wondering whether a human being capable of reading has answered. Can't see why you should wonder how so-called "experts" could provide completely different answers to the same question. After some 8 months exposure to the Out&AboutLive motorhome forums, I would have thought you would have become used to that by now! ;-) Link to comment Share on other sites More sharing options...
Corky 8 Posted April 4, 2009 Share Posted April 4, 2009 Hi, here,s the letter I received from Michelin when enquiring about my tyre pressures, seems I would have to weight each axle empty then loaded, a lot of messing to conform with. Thank you for your recent e-mail. If you could please supply further information such as the actual axle loads, we can then supply definitive tyre pressures, please read our information as detailed below:- We suggest that individual axle weights from weigh scale readings (from a local weigh bridge) are used, in order to calculate pressure recommendations for each quoted load condition. These would be preferred, due to readings being taken in the actual vehicle 'running' condition - that is to say, with all water/fuel/baggage & passengers etc. onboard - and may result in better comfort if the vehicle is running way below maximum capacity. The results of roadside surveys indicate that some motor homes have been found to be over laden, especially the rear axle, with potential for subsequent tyre related problems. The overall tyre industry, therefore, tries to build-in a safety factor by fitting strong tyres, inflated to high pressure, in order to remove the potential for consequences of overloading &/or under-inflating the tyres. The drawback of this safety factor, at the corresponding high pressure, may be an extremely hard ride. The contents of the motor home may rattle, but the tyres will cope nicely. Unfortunately one 'overall' weight is of no use in calculating tyre inflation pressure levels, since the vehicle may appear to be within the maximum permitted, but in reality may have the rear axle severely over laden & the front axle very lightly laden. We have allocated your message the reference number indicated above. If you need to contact us again regarding your message, we would be grateful if you could include the reference number. Once again thank you for your interest in Michelin. Yours sincerely Michelin Tyre Public Limited Company Link to comment Share on other sites More sharing options...
dikyenfo Posted April 4, 2009 Share Posted April 4, 2009 Very confusing and the other thing I can never understand is the fact that motor homes are on the small tyres that never get used by the commercial frat. EG my Iveco van has the same rims as the MH but 225 is the industry standard when it comes to these tyres for the Iveco so why done we use the fatter tyre when we have to change rubber? Typically a set of federals [various patterns] are 50 quid fitted and balanced. They also give a better ride and handling than Aquilis. Link to comment Share on other sites More sharing options...
Mike Chapman Posted April 4, 2009 Share Posted April 4, 2009 dikyenfo - 2009-04-04 11:44 AM Very confusing and the other thing I can never understand is the fact that motor homes are on the small tyres that never get used by the commercial frat. EG my Iveco van has the same rims as the MH but 225 is the industry standard when it comes to these tyres for the Iveco so why done we use the fatter tyre when we have to change rubber? Typically a set of federals [various patterns] are 50 quid fitted and balanced. They also give a better ride and handling than Aquilis. Hello Dikyenfo, Not sure about the point that you are making but there are many Motor Caravans supplied with 225 section tyres (My last van was supplied with 225/65R16 Continentals as standard). To the best of my knowledge all of the tyre manufacturers who supply special Camping Car versions in their tyre range have 225 section versions eg. Agilis Camping 225/75R 15CP 116Q. The size and type of tyre is specified and tested by the Manufacturer and Coachbuilder taking GVW into consideration. In addition changing to a wider section tyre may upset the handling and could foul suspension or body sections. It is possible to "Overtyre" a vehicle as well as "Undertyre". Regards, Mike. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted April 5, 2009 Share Posted April 5, 2009 dikyenfo - 2009-04-04 11:44 AM the other thing I can never understand is the fact that motor homes are on the small tyres that never get used by the commercial frat. This is a fallacy. It's plain when one studies manuals provided by the manufacturers of the vehicles on which motorhomes are based, and tyre manufacturers' technical handbooks, that it's normal for a range of 'van' chassis to have a variety of different tyre sizes as original equipment. When a motorhome converter purchases a chassis from Ford, Fiat, Iveco, etc. it will arrrive at the converter's factory either with the standard tyres it was fitted with on the Ford, Fiat, Iveco, etc. production line, or with specialised 'camper' tyres that have been chosen with the foreknowledge that the chassis is destined to become a motorhome. In the latter case the 'camper' tyre will ALWAYS be the same size as the 'standard' tyre appropriate to that chassis. This is necessary for EC homologation reasons. In France, a vehicle's original tyre details are recorded on its registration document and it's part of the French MOT-test equivalent to check that a vehicle's tyre details are unaltered. Apparently this has caused problems with older motorhomes whose original Michelin-made 'camper' tyres are no longer in production. Owners have replaced such tyres with the next width up in the Michelin Camper range and then had their motorhomes fail the French MOT. There was a complaining letter about this in a recent French motorhome magazine and the advice was to fit the replacement, larger camper tyres to a different set of wheels and put the original wheels/tyres back on to the motorhome just for the test inspection. Link to comment Share on other sites More sharing options...
clifty Posted April 8, 2009 Share Posted April 8, 2009 Hi I,ve recently bought a 2005 Rapido based on the Fiat Chassis with a 3850kg upgrade. The door pillar sticker reccommends 5.5bar all round. After pumping up from approx 5 bar we find the ride pretty harsh and am considering dropping back to 5 bar. :-S Link to comment Share on other sites More sharing options...
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