cleddytanhouse Posted July 16, 2016 Share Posted July 16, 2016 It may seem a bit obvious, however, are the stated tyre Pressures as shown on the base vehicle door plate, correct for when the vehicle has been converted? My plate states 5.5 bar or approx 76psi for my 4.25 ton Autotrail. I have just measured my pressures and they are only approx 4.0 bar or 50psi. My normal car electric pump cannot pump the required high pressure, so, a trip to the garage is required to obtain the correct pressures. Link to comment Share on other sites More sharing options...
david lloyd Posted July 16, 2016 Share Posted July 16, 2016 Not usually. Most converters simply leave the tyres at the pressure for the base vehicle and are usually at their highest level - up to 89 psi. Now that may be correct for your Motorhome but it is unlikely. The only real way to get the correct tyre pressures is to weigh each axle when fully loaded and email the tyre technical department of your tyre manufacturers with all the details of tyre size/speed rating/weight rating etc and your axle weights. They will advise what the pressures should be. As an example, my tyres were set at 79 psi rear and 76 front but when I went through this procedure Continental advised 60.2 rear (axle weight of 2240kgs) and 50.4 front (axle weight of 1610kg) which gives a far better ride and handling. David Link to comment Share on other sites More sharing options...
Billggski Posted July 16, 2016 Share Posted July 16, 2016 Camper tyre manufacturers, mainly Michelin and Continental, recommend the maximum, 5.5bar on the rear, whatever the load. Presumably to cover themselves. Normal white van tyres won't go that high, so visit a weighbridge, find each axle weight, and search for the appropriate pressure for the tyres you have fitted. I just google "camper van tyre pressures" Link to comment Share on other sites More sharing options...
Keithl Posted July 16, 2016 Share Posted July 16, 2016 Or download the MH tyre brochure from the 'TyreSafe' website and use that to get an idea of what pressure you should be running at. Sorry but I haven't got a link to hand. Keith. Link to comment Share on other sites More sharing options...
david lloyd Posted July 16, 2016 Share Posted July 16, 2016 Billggski - 2016-07-16 6:02 PM Camper tyre manufacturers, mainly Michelin and Continental, recommend the maximum, 5.5bar on the rear, whatever the load. Presumably to cover themselves. Normal white van tyres won't go that high, so visit a weighbridge, find each axle weight, and search for the appropriate pressure for the tyres you have fitted. I just google "camper van tyre pressures" Have to disagree that the main manufacturers only recommend the maximum pressure. As I mentioned earlier, I have just had appropriate pressures advised by the technical department at Continental tyres and, some years ago, had the same help from Michelin. In addition, tyre pressures should vary with the weight on the axles, tyre size etc so googling 'camper van tyre pressures' may give you some tyre pressures but not necessarily the best for individual circumstances. David Link to comment Share on other sites More sharing options...
Malo37 Posted July 16, 2016 Share Posted July 16, 2016 Billggski - 2016-07-16 6:02 PM Camper tyre manufacturers, mainly Michelin and Continental, recommend the maximum, 5.5bar on the rear, whatever the load. Presumably to cover themselves. Normal white van tyres won't go that high, so visit a weighbridge, find each axle weight, and search for the appropriate pressure for the tyres you have fitted. I just google "camper van tyre pressures" Incorrect I'm afraid. Below is an email I received from Continental. " Based on the following: ContiVanco 2 235/65 R16 C 15/113 tyres. Front Axle: 1532 Kg - 3.0 bar/ 43.5 psi (maximum weight 1680 kg) Rear Axle: (single fitment) 1758 Kg - 3.25 bar/ 47.1 psi (maximum weight 1795 kg) Rear Axle: (twinned fitment) 1758 Kg – 3.0 bar/ 43.5 psi (maximum weight 3185 kg) I hope this helps and any further enquiries (no matter how small) please do not hesitate to ask, we are always happy to help! Best Regards Alex Wilson Product Support Engineer Visitors Address: Continental Tyre Group Ltd DC2 Castle Mound Way Rugby United Kingdom CV23 0WB " Link to comment Share on other sites More sharing options...
Billggski Posted July 17, 2016 Share Posted July 17, 2016 Sorry, I thought that's what I said, if you find your actual weight they can recommend the correct pressures, or you can look them up yourself. if you just ask for a pressure they say 5.5 bar to cover themselves. Link to comment Share on other sites More sharing options...
Robinhood Posted July 17, 2016 Share Posted July 17, 2016 Malo37 - 2016-07-16 11:40 PM Incorrect I'm afraid. Below is an email I received from Continental....... The current Continental Technical Databook is available for download here: http://www.conti.nl/wp-content/uploads/2015/08/Databookcar-4x4-van-2015-16.pdf ...and (as you would hope) confirms the above values for non-CP rated tires (slightly higher rear recommendation for CP tyres). If you have Continental tyres, this is a useful resource. Link to comment Share on other sites More sharing options...
mikebeaches Posted July 17, 2016 Share Posted July 17, 2016 Agree with everything that has been said about Continental tyres and how helpful the company is in its willingness to advise the correct tyre pressures. For whatever reason, they tend to be much lower pressures than those indicated by either the original van manufacturer or the the converter. And the lower pressures provide a MUCH more comfortable ride. Unfortunately, the new Rapido pvc I've just taken delivery of has Michelin tyres fitted. What's the problem? I've had Michelins fitted on my cars for years and they're fine. But, from previous experience, Michelin always recommended no less that 80psi for the rear tyres on any MH or camper, regardless of the axle weight! :-( Which presents something of a dilemma. It makes the ride so harsh that the fillings in my teeth will soon come loose. But do I judiciously reduce the tyre pressures? Would that be unsafe? Would it invalidate my insurance? Would it put me in conflict with the law? Suggestions welcome... Link to comment Share on other sites More sharing options...
david lloyd Posted July 17, 2016 Share Posted July 17, 2016 mikebeaches - 2016-07-17 1:41 PM Agree with everything that has been said about Continental tyres and how helpful the company is in its willingness to advise the correct tyre pressures. For whatever reason, they tend to be much lower pressures than those indicated by either the original van manufacturer or the the converter. And the lower pressures provide a MUCH more comfortable ride. Unfortunately, the new Rapido pvc I've just taken delivery of has Michelin tyres fitted. What's the problem? I've had Michelins fitted on my cars for years and they're fine. But, from previous experience, Michelin always recommended no less that 80psi for the rear tyres on any MH or camper, regardless of the axle weight! :-( Which presents something of a dilemma. It makes the ride so harsh that the fillings in my teeth will soon come loose. But do I judiciously reduce the tyre pressures? Would that be unsafe? Would it invalidate my insurance? Would it put me in conflict with the law? Suggestions welcome... Hi, it was a few years ago now but I did once contact Michelin technical department with the relevant information (tyre size, speed rating, axle loadings etc) and they obliged with revised tyre pressures for the Camping tyres. David Link to comment Share on other sites More sharing options...
mikebeaches Posted July 17, 2016 Share Posted July 17, 2016 david lloyd - 2016-07-17 3:43 PM mikebeaches - 2016-07-17 1:41 PM Agree with everything that has been said about Continental tyres and how helpful the company is in its willingness to advise the correct tyre pressures. For whatever reason, they tend to be much lower pressures than those indicated by either the original van manufacturer or the the converter. And the lower pressures provide a MUCH more comfortable ride. Unfortunately, the new Rapido pvc I've just taken delivery of has Michelin tyres fitted. What's the problem? I've had Michelins fitted on my cars for years and they're fine. But, from previous experience, Michelin always recommended no less that 80psi for the rear tyres on any MH or camper, regardless of the axle weight! :-( Which presents something of a dilemma. It makes the ride so harsh that the fillings in my teeth will soon come loose. But do I judiciously reduce the tyre pressures? Would that be unsafe? Would it invalidate my insurance? Would it put me in conflict with the law? Suggestions welcome... Hi, it was a few years ago now but I did once contact Michelin technical department with the relevant information (tyre size, speed rating, axle loadings etc) and they obliged with revised tyre pressures for the Camping tyres. David Thanks David - I recall they used to operate in much the way Continental do and match tyre pressures to axle load. But all of a sudden they changed policy and refused to offer anything other than minimum 80psi on the rear for motorhomes on camping tyres. I challenged them on one occasion, but they weren't having any of it at the time. They were willing to match axle weight to tyre pressure for the front wheels, but not the back. Unless anybody has had success recently, I don't think they've changed their policy. Link to comment Share on other sites More sharing options...
david lloyd Posted July 17, 2016 Share Posted July 17, 2016 mikebeaches - 2016-07-17 4:24 PM david lloyd - 2016-07-17 3:43 PM mikebeaches - 2016-07-17 1:41 PM Agree with everything that has been said about Continental tyres and how helpful the company is in its willingness to advise the correct tyre pressures. For whatever reason, they tend to be much lower pressures than those indicated by either the original van manufacturer or the the converter. And the lower pressures provide a MUCH more comfortable ride. Unfortunately, the new Rapido pvc I've just taken delivery of has Michelin tyres fitted. What's the problem? I've had Michelins fitted on my cars for years and they're fine. But, from previous experience, Michelin always recommended no less that 80psi for the rear tyres on any MH or camper, regardless of the axle weight! :-( Which presents something of a dilemma. It makes the ride so harsh that the fillings in my teeth will soon come loose. But do I judiciously reduce the tyre pressures? Would that be unsafe? Would it invalidate my insurance? Would it put me in conflict with the law? Suggestions welcome... Hi, it was a few years ago now but I did once contact Michelin technical department with the relevant information (tyre size, speed rating, axle loadings etc) and they obliged with revised tyre pressures for the Camping tyres. David Thanks David - I recall they used to operate in much the way Continental do and match tyre pressures to axle load. But all of a sudden they changed policy and refused to offer anything other than minimum 80psi on the rear for motorhomes on camping tyres. I challenged them on one occasion, but they weren't having any of it at the time. They were willing to match axle weight to tyre pressure for the front wheels, but not the back. Unless anybody has had success recently, I don't think they've changed their policy. How strange.......you wonder where they come up with these policies. Still, I like the Continentals -and the fact they will assist - and they have taken the time to reply on this thread. David Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 17, 2016 Share Posted July 17, 2016 As has been said several times before on this forum Michelin is merely following the advice of the ETRTO (European Tyre and Rim Technical Organisation) about operating “CP”-marked tyres on a motorhome’s rear axle at a pressure of 5.5bar (80psi). See Page 46 of this 2014 document http://www.pneusnews.it/wp-content/uploads/sites/7/2013/08/ETRTO-RECOMMENDATIONS-EDITION-25-SEPTEMBRE-2014.pdf Continental takes a less rigid stance regarding providing pressure-to-axle-weight data for “CP”-marked tyres, but it’s the ETRTO that’s the driving force behind Michelin’s rigid attitude. If the Michelin tyres fitted to Mike’s Rapido PVC are not “CP”-marked (which is quite likely) Michelin will be perfectly happy to provide pressure-to-axle-weight advice for both front and rear axles of the vehicle. If the tyres are “CP”-marked Michelin will advise 5.5bar for the rear axle irrespective of a measured axle-load being provided by the vehicle’s owner, but will advise a potentially lower pressure for the front axle. Can’t comment on the legal position: as far as I’m concerned the tyre-pressures in the motorhome’s handbooks must be considered ‘correct’, even though they may be far from optimum. Link to comment Share on other sites More sharing options...
cleddytanhouse Posted July 17, 2016 Author Share Posted July 17, 2016 Having started this question, today, I did what I should have done first. I looked in the Autotrail handbook, which clearly states for my MH the correct pressure is 5.5 bars. So, it is off to my local petrol station to check my tyres. Thanks for all the advice. Link to comment Share on other sites More sharing options...
mikebeaches Posted July 17, 2016 Share Posted July 17, 2016 Derek Uzzell - 2016-07-17 6:53 PM As has been said several times before on this forum Michelin is merely following the advice of the ETRTO (European Tyre and Rim Technical Organisation) about operating “CP”-marked tyres on a motorhome’s rear axle at a pressure of 5.5bar (80psi). See Page 46 of this 2014 document http://www.pneusnews.it/wp-content/uploads/sites/7/2013/08/ETRTO-RECOMMENDATIONS-EDITION-25-SEPTEMBRE-2014.pdf Continental takes a less rigid stance regarding providing pressure-to-axle-weight data for “CP”-marked tyres, but it’s the ETRTO that’s the driving force behind Michelin’s rigid attitude. If the Michelin tyres fitted to Mike’s Rapido PVC are not “CP”-marked (which is quite likely) Michelin will be perfectly happy to provide pressure-to-axle-weight advice for both front and rear axles of the vehicle. If the tyres are “CP”-marked Michelin will advise 5.5bar for the rear axle irrespective of a measured axle-load being provided by the vehicle’s owner, but will advise a potentially lower pressure for the front axle. Can’t comment on the legal position: as far as I’m concerned the tyre-pressures in the motorhome’s handbooks must be considered ‘correct’, even though they may be far from optimum. You certainly are a mine of information Derek! I am sure you are correct - the ETRTO recommendations are what is causing Michelin to insist on 80 psi (5.5 bar) on the rear axle. Personally, I find the guidelines disingenuous - referring to motohomes and CP-marked tyres "...a study which demonstrated, that overloading is generally the main cause of tyre failure, due to the fact that this type of vehicle often carries an excessive or badly distributed load..." In other words, we're all tarred with the same brush, and have to have sub-optimal (and uncomfortable) tyre pressures because according to ETRTO folk overload motorhomes. :-( Unfortunately, for me, in this instance, my tyres are marked 'CP'! Thanks anyway Derek - I will think on as to how best to resolve the situation. And apologies to the OP for somewhat hijacking his thread, though hopefully the minutiae of the subject will have been of interest. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 18, 2016 Share Posted July 18, 2016 Mike There’s little difficulty obtaining ‘safe and suitable’ inflation pressures for “CP”-marked tyres based on a Ducato-based motorhome’s axle-loadings measured on a weigh-bridge. However, choosing to use such pressures will inevitably conflict with Fiat’s advice and (most probably) with that of the motorhome manufacturer. You asked whether reducing the Fiat-advised pressures would invalidate your insurance and put you in conflict with the law. The answers are maybe and possibly. You could explore this with your insurance provider and the relevant authorities, and the best of luck! Like adultery you either do it or you don’t - if you are really concerned about risk and legality, best you don’t. Link to comment Share on other sites More sharing options...
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