Tyre pressure/bar query HELP???

Discussion in 'Tech/Mech General' started by motorhomemania, Jun 23, 2009.

  1. motorhomemania

    motorhomemania Read Only Funster

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    Hi all,
    Is there any one out there who can give advice on the tyre pressure/bar for a
    225/75 R16 CP tyre on a burstner elegance i821 08 plate fiat ducato engine 160bhp/ 3 litre engine.
    After discussing with several people including a chap on a Burstner number in this country, a tyre garage near our home and two people who own same vehicle we still have different opinions.
    According to fiat book the use I presume will be Heavy range with camping tyres(not oversize tyres) and this says front 5.5+ - 0.05 rear 5.5 + - 0.05 .
    We have also been told that 1 bar is equal to 14llbs.
    Please can anyone help as we are hoping to go to France in the near future and are concerned about their strictness on driving rules and regs???!!!
    Sorry to be so long winded but....................HELP!
    Cheers,
    Nic and Steve (MEANY):Confused:
     
  2. Decmac

    Decmac Read Only Funster

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    tyre pressure bar query/help

    I have a Burstner Aviano i684 in my possession. Now it's dark outside at the moment but I will check in the morning and see if the tyres are the same dimensions as yours, just can't remember offhand, pretty sure they are though. Will let you know 2morrow. Hope you can wait
    Decmac
     
  3. vwalan

    vwalan Funster

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    sounds about right. i always say i bar 15lbs earier to remember .keep an eye on the tread wear and adjust to suit. if edges of tread wear inflate more . if centre wears deflate .5 bar its trial n error . most tyre pressures are guesstimates.
     
  4. Decmac

    Decmac Read Only Funster

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    Tyre pressure

    Yeah, just checked mine about a minute ago. My tyres are exactly the same as yours . . . 225/75 R16CP. I have the owner handbook here and it says: Tyres - 225/75 R16 CP; Use - Heavy range with Camping tyres; Front - 5.5+0.05; Rear - 5.5+0.05. Hope this helps you. There's other bits and pieces of information about the tyres also on the handbook which I can send if you want. Is the +0.05 info extra pressure when you have an extra load, I don't really understand that. Maybe you can explain that to me if you wouldn't mind.
    Anyway enjoy the trip to France. We're not going this year as I have had a bit of a health problem so we'll have to wait until next year. If you have a handbook you'll get all the information I am giving you on the very last page (or maybe you can borrow one). I can send you this information if you like by e-mail. My address is decmac40@yahoo.ie. Happy travelling.
    - Decmac
     
  5. madbluemad

    madbluemad

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    Hi
    This is a convaluted subject and you will get different answers from different people

    One Bar equals 14.5037738 PSI (GOOGLE) but I knew that anyway :Cool:. So 14 or 15 take your pick. You lose that much pressure when uncoupling from your tyre valve.

    My tyres are 225/75/R16. They say on the side wall 80 PSI MAX COLD. I have a label inside my van which gives me the tyre pressure for each tyre based upon the weight that I am carrying and thats the important part. Weight and to a lesser degree Speed Rating. At the reccomended pressure in Bar you must be putting 79.95 PSI into your tyres.

    I dont know the weight of your van but 79 PSI sounds excessive.

    If you know the weight of your vehicle and you should do, give somebody like Michelin a ring and they will tell you what pressure to put in your tyres base on wheel size, weight, (Load Index) and Speed Rating.

    I do sympathise with you but its easy once you have it soughted. There are loads of posts on here concerning tyre pressures, just do a search and you will get loads of info.

    Cheers
    Jim
    :Smile:
     
    Last edited: Jun 24, 2009
  6. pappajohn

    pappajohn Funster Life Member

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    5.5 bar or 79.95 psi is the absolute maximum safe pressure of your tyres at their weight rating....not your normal tyre pressure.

    i would say 65psi rear and around 60psi front.

    in my opinion, 80 psi would be dangerous under normal conditions and the ride would be very harsh, not to mention excessive central tyre wear.

    have a look <<HERE>> then click the download button to get a better idea what they should be.

    you need to scroll near the bottom to find the charts and you need your axle weights, front and rear, not the gross weight.
     
    Last edited: Jun 24, 2009
  7. Chudders

    Chudders Read Only Funster

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    If your tyres of that size are Michelin XC camping or Agilis, ring Michelin for their advice. I did and was told that following discussion with VOSA the only advice they are permitted to give is that rear tyres should be inflated to 80PSI. (The maximum) The front tyres however they are permitted to vary advice dependent on axle loads given. I assume that this is the same for all tyre manufacturers who have been in this discussion with VOSA. I couldn,t quite bring myself to inflate my 225/R16 tyres to 80 so I run them at 75PSI. Can,t honestly say I have noticed a particularly hard ride.
    Dave
     
  8. pappajohn

    pappajohn Funster Life Member

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    i think i would ask for that in writing from michelin.

    if you have an accident and your tyre pressures are incorrect the insurance company have an instant 'get out' excuse.
    if VOSA state run at maximum 80psi you then have a 'retort' and COULD hold VOSA responsible.
    tyre pressures are there for a reason.
    iv been in a car with 50psi all round (unknowingly)and they think 'teflon' is non stick:Eeek:

    i cant see how michelin can give advise on front pressures but not rears....doesnt make sense.
     
  9. Chudders

    Chudders Read Only Funster

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    I do have it in writing for that very reason, They e mailed me the information including the front recommended pressures for the axle weights I gave them. The reason given was that VOSA consider that motorhomes seem to be loaded often to their maximum weight (if not over) and this is the reason for their advice. I was also informed that in a roadside check these pressures are what VOSA would expect. I am of course only talking about Michelin tyres. I just assume that other manufacturers are doing the same.
    I now carry in the van a copy of that e mail with other documents.
    Dave
     
  10. Decmac

    Decmac Read Only Funster

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    Tyre pressure

    Very good idea to have it in writing from the manufacturer. Then the insurance company can't 'get out' as you say if something (God forbid) happens. My tyres are made by Continental so I must get in touch with them and see what they say. Then again they could refer me back to the handbook (i.e. passing the buck) but I'll try them anyway
    - Decmac
     
  11. Chudders

    Chudders Read Only Funster

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    I have today had an e mail from Michelin and they have again recommended 80 psi for my rear axle weight of 2220Kg and 65 psi for front axle weight of 1750Kg.
    When I asked previously I quoted 2100 Kg rear axle and the reply was that those tyres will always attract a recommendation from them of 80psi. They will vary the front pressures and take into account the axle load and weight transference when braking and cornering etc. It appears to me that 80psi will be the standard response and recommendation. In the event of a roadside check or an accident it would be difficult to suggest other pressures are appropriate if Michelin are prepared to continue with this recommendation as I understood this was as a result of roadside surveys.
    I would be interested to know if any one else has had, or is going to contact Michelin particularly to see if the advice is the same as I have had.
    Nothing seems to be straightforward, (or is it)
    Regards to all, Dave
     
  12. sinbad1

    sinbad1 Deleted User

    I had a simular query Michelin reply :

    Dear Mr XXXXX

    Thank you for your recent e-mail.

    We suggest that individual axle weights from weigh scale readings 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.

    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.

    As a guideline from the axle weights that you have supplied on tyre size 215/70 R15 C (if the XC Camping tyre) the pressures for those weights should be as follows:-

    Front axle load of 1600kg the pressure should be – 55 psi (pounds per square inch)
    Rear axle load of 1650kg the pressure should be – 50 psi (pounds per square inch)

    The Front axle pressure in this case may be higher than the Rear even though the axle load is lower. Therefore the slight increase in pressure which has been added to the front axle is due to the braking forces and shift in weight that’s being exerted onto it.

    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


    Its my opinion that at 80psi as recomended by my manufacturer is Max and in most cases is OTT.
    regards
     
  13. pappajohn

    pappajohn Funster Life Member

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    according to the tyre pressure download ( under 'tools' in downloads)
    front wheel drive, single wheel, single rear axle....

    the rears should be 68psi

    the fronts should be 57psi (both adjusted down for the slight weight difference)

    this is for a 225/70/16cp.....they dont list a 225/75/16cp.

    this download is from the british tyre manufacturers association website

    but who am i to argue with michelin.:Sad:
     
  14. madbluemad

    madbluemad

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    Hi Pappa

    The British tyre manufacturers association coudnt tell me what the difference was between a European and American tyre marking specification so :Doh:

    Cheers

    Jim
    :thumb:
     
  15. pappajohn

    pappajohn Funster Life Member

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    thats cos they only deal with british tyres:Doh::Rofl1::Rofl1::Rofl1:
     
  16. gazznsam

    gazznsam Read Only Funster

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    i always ask the tyre makers for advise on tyre pressures, they will need the individual axle weights, and if the rears are dual or single wheels, as well as the exact tyre size and model you have,

    i usually run goodyear cargo tyres on my van, but have a pair of avon AV9's on the front due to not being able to get a goodyear G26 to match the others when i picked up a nail too close to the sidewall a few months ago,
    These are 215, 75 x 16 commercial rated tyres,

    avon told me the absolute minimum safe pressure would be 44psi for my fronts, and if i had their tyres on the dual rear wheels, then 36psi in them would be the minimum, this is based on the axle weights i gave them of 1600 kilos front, 2600 kilos rear.

    goodyear tell me around 40psi for the rears,
    that will sound low, but the load is shared over 4 tyres at the back, where as most motorhomes have single rear wheels, hence the need for the reinforced tyres and higher pressures.

    i run at 50 psi fronts, and 45 rears, this seems to get me the best grip, best ride, and they are wearing nice and evenly accross the tread, so arent underinflated,
    i also check the tyre temperatures every so often on a long journey with an infared temp gun, i do this mainly to spot a tyre loosing pressure which will run hotter than the rest, easier than checking the actual pressures when on a journey,
    but my tyres dont run hot, so i seem to have the pressures right for my vehicle, but even if someone had exactly the same as mine, same layout etc, they would prolly run a slightly different pressure as they'd have it loaded differently,
     
  17. madbluemad

    madbluemad

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    I would expect an organisation like the British Tyre Manufacturers Association to be aware of the various tyre marking specifications in place throughout the world and what they mean particularley given the most of the tyres manufactured for the uk market are munufactured abroad. :Doh:

    Jim

    :Smile:
     
  18. ralph-dot

    ralph-dot Read Only Funster

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    Can I just mention that there are too many scary stories about French rules and regs and also French police, do not worry about that part of your trip just enjoy it.

    Ralph
     
  19. pappajohn

    pappajohn Funster Life Member

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    agreed Jim, but no matter where they are made the markings are for the uk/euro market which would be their only concern.
    why would they need to know the markings for foreign countries.
     
  20. madbluemad

    madbluemad

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    Hang on Pappa, I'll think of one and get back :Laughing:

    Jim
    :Smile:
     
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