Tyre Pressure Guidance Please

Discussion in 'The Beginner' started by oldflemo, Jun 21, 2015.

  1. oldflemo

    oldflemo Funster

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    Hi Guys,
    Fitting a TyrePal today on the MH and not being able to find any guidance on tyre pressures for the new to us Lunar Roadstar 620 I decided to check the tyre pressures Marquis had set it up with. I was surprised that the front tyres are set at 73 psi and the rear 80 psi . I had expected the higher pressure to be on the front axle.
    Am I being stupid(which is highly likely as I usually am!) expecting the axle carrying the engine to require the greater tyre pressure?
    I am aware that I need to go to a weighbridge to be able to calculate the required/correct pressures but just wondered if I got the principle incorrect.
    Look forward to your guidance --thanks again
    Ian
     
  2. pappajohn

    pappajohn Funster Life Member

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    Front axle is always lighter than the rear so tyre pressures should correspond.
    always more weight on the rear, even with the engine sat over the front axle

    My old kontiki 640, 2850kg, ran at 60psi rear and 52psi front
    my current 7500kg rv runs 80psi front and rear but the weight split is around 60% rear and 40% front so no hard and fast logic.
     
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  3. oldflemo

    oldflemo Funster

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    Thank you Pappajohn -my assumptions are wrong again -no change there then!
    Ian
     
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  4. emmitdb

    emmitdb Funster

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    Oldflemo,

    Come back when you have the weights on each axle and tell us what tyres your outfit is wearing. (It makes a difference as to whether it's got Light Commercial or Camping tyres) It would also help if you could say in what trim the 'van was in when it was weighed, (Loaded to the Gunwhales or nothing in it.)
    Then an answer can be given that will suit your own particular circs.
    Just because Marquis put those pressures in, don't make it right.
     
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  5. Techno

    Techno Funster Life Member

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    Without my garage loaded my front is lots heavier than rear
     
  6. NickNic

    NickNic Funster Life Member

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    @oldflemo There is only one way you can get the correct pressures.

    You have to email the manufacturers of the tyres with the details of your tyres and the axle weights (preferably weighed but plated if not) and they will come back to you with the correct pressures for those particular tyres at those weights.

    Nobody else can give you a correct answer as the weights vary from manufacturer to manufacturer. They are all used to answering this sort of query and will get back to you quite quickly.

    The rear will be higher than the front though. On mine, with Michelins fitted, the front is at 62psi and the rear is at 80psi.
     
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  7. oldflemo

    oldflemo Funster

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    Thank you again guys for your advice- I plan to go to the weighbridge and then do as NickNic recommends
    Ian
     
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