Tire Pressures

Discussion in 'Tech/Mech General' started by madbluemad, Jul 26, 2008.

  1. madbluemad

    madbluemad

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    Hi Folks

    I had a new tire fitted about four weeks ago. I asked the fitter to check all of the tires at the time.

    He checked them and they were all at 70 psi. The information printed on the tire says 80 psi cold. I asked the fitter to take them to 80 psi but he said that 80 was to high and that 70 was the optimum pressure.

    I have just checked my tire pressures and they vary from 70 psi to 55 psi. This may be because its very hot on one side of the van and relatively cool on the other side.

    Whats your opinion and what pressure should my tires be inflated to.

    Cheers

    Jim :Sad:
     
    Last edited: Jul 26, 2008
  2. madbluemad

    madbluemad

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    Please delete post, I have the answer. Unless of course its of any use to others.

    Jim :thumb:
     
  3. TJ-RV

    TJ-RV Deleted User

    For the benefit of others who might see this in future, the tyre pressure on the wall of a tyre is the maximum pressure. Correct tyre inflation pressure is best determined by separately weighing the four corners, or at least weighing each axle, and using the load/inflation tables on the tyre manufacturer's web site.

    Care to share that for the benefit of others?
     
    Last edited by a moderator: Jul 26, 2008
  4. landau

    landau Deleted User

    Tyre Pressure

    I work in the workshop of a motorhome dealer (American and European) and 10psi under the cold pressure which is marked on the tyre is the rule of thumb, hope this helps .
     
  5. haganap

    haganap Funster Life Member

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    Mine are set at 70psi, exactly 10psi undr the maximum.
     
  6. pappajohn

    pappajohn Funster Life Member

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    mine are 65psi rear and 62psi front on a 2.85 tonne kontiki 640.
     
  7. TJ-RV

    TJ-RV Deleted User

    Some fixed number below the maximum makes little sense. If the tyres are replaced somewhere down the road by some with a different maximum pressure, do you then adjust the inflation pressure down or up even though the load on the tyres hasn't changed?

    Check the load/inflation tables on the tyre manufacturer's web site to determine the correct pressure for a given load. Here, as an example, is GoodYear's load/inflation table. Note that, in addition to the required pressure varying by load on the inidividual tyre, it also varies depending on whether the tyre is mounted single or as one of a pair (aka duallies).

    Underinflation is a recipe for a blowout, while overinflation will likely result in unexpected wear patterns in addition to poor ride and handling characteristics.

    With due respect to dealers and repair shops, I've yet to come across one that has any clue what load is being carried by tyres or, for that matter, who have heard of the load/inflation tables.

    When we bought our coach from a dealer, there was a truck weigh scale next door, although the dealer had obviously never used it. The PDI tech assured me he had checked and correctly inflated the tyres to 120 psi. I checked them (cold) and found they were inflated to 140 psi, which was higher than the rating on the rims. After weighing the coach and consulting the tyre manufacturer's table, I found the correct inflation pressures to be 90 psi in the front and 95 psi in the rear.
     
    Last edited by a moderator: Jul 27, 2008
  8. Tony Santara

    Tony Santara Funster

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    Care to share that for the benefit of others?[/QUOTE]

    Hi tom
    Looks like Jim (madbluemad) doesn't want to share :Smile:

    Oh well maybe he'll want us to share info with him next time :Wink:
     
  9. TJ-RV

    TJ-RV Deleted User

    Tony,

    Given the nature and intent of forums such as this (i.e. sharing of knowledge, information and experience for the mutual benefit of the members), I don't understand why anyone would ask questions but not share answers. I understand even less a request to remove their question after they have their answer.

    OTOH I've been around forums many years and nothing surprises me anymore.
     
    Last edited by a moderator: Jul 27, 2008
  10. TJ-RV

    TJ-RV Deleted User

    Here's a useful read on RV tyre care on GoodYear's web site.
     
  11. Tony Santara

    Tony Santara Funster

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    Good link Tom
    my tyres will never suffer from prolonged storage they get used as often as i can , I have had 2 blown tyres in the last 3 years but they were degraded from use :thumb:
     
  12. TJ-RV

    TJ-RV Deleted User

    Tony,

    We don't worry about tyre pressures on our other RV :BigGrin:

    Weight isn't an issue either; She'll carry more than I could think of loading on board. Plenty of spare HP too, and no brakes to worry about.
     
  13. madbluemad

    madbluemad

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    Care to share that for the benefit of others?

    Hi Tom
    Its simple, the tire pressures are printed on a label inside the coach, this is a federal ID tag that must be inside the coach.

    Ive had a lot to do with tires recently and you are correct in saying that the most accurate way to identify the correct inflation pressures is to weigh the vehicle.

    Different loads require different inflation pressures. The problems start when you have an American tire on your coach, you try to replace it and find that the US system of identification is different to the UK one.

    I spoke to the CC&C, two local tire dealers, kwik Fit, Michelin, Ford, Hankook, Gulfstream and a host of others. None of them new what the equivalent UK specification was to the US one. PATHETIC

    In the end it came down to taking some of the info from the US tire and then making reference to the coach weights which again are posted on the inside of the coach.

    Whats more disturbing for me is why did my tire pressures change by such a varying degree after only about five weeks.

    Ive invested into a good quality tire pressure Gauge so that I can now check more often.

    Cheers

    Jim :thumb:
     
  14. madbluemad

    madbluemad

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    That would account for all of the tires being at 70 psi when they are marked 80 psi cold. :thumb:
     
  15. madbluemad

    madbluemad

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    Hi tom
    Looks like Jim (madbluemad) doesn't want to share :Smile:

    Oh well maybe he'll want us to share info with him next time :Wink:[/QUOTE]

    What seems to be your problem then. As it happens Ive been logged off and only just seen the posts, the first one I read was from TJ and I responded immediatley. Then I read your not to pleasant piece of graffiti.

    Grow Up
     
  16. madbluemad

    madbluemad

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    SAD Try get your facts right before engaging the mouth
     
  17. Tony Santara

    Tony Santara Funster

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    OOPS looks like we touched a nerve ...:BigGrin:
     
  18. madbluemad

    madbluemad

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    You got that one right. I will help anybody at anytime and they dont need to be a member of an internet forum

    Had you read my initial post you would have seen that I said " Leave it on if its of interest to others"

    I then left my computer. Upon my next visit to the forum I find that you have incorrectley accused me of being unhelpful and unwilling to help people or share my knowledge/information.

    This could not be further from the truth. You then led TJ by the nose and he joined in the attampted character assaination.

    Big Grins dont do it son, you can be as arrogant and as nasty as you like but not with me.

    Like I said Grow Up
     
  19. Tony Santara

    Tony Santara Funster

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    I'm not getting into it on the forum with you it's not the place for personal arguements .

    Ill feeling could have been avoided if you had explained the answer you had found at the time you said you'd found it ...simple
     
  20. hawkeye6007

    hawkeye6007 Read Only Funster

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