UNUSUAL TYRE WEAR - ELAINE'S MK4 25J

Discussion in 'Wheels and Tyres' started by Dave, Dec 24, 2021.

  1. Dave

    Dave Pedantic Old Fart Paid Member

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    Hi Folks - Long Time No See

    For those who don't know Elaine's car:
    2002 Mk4 25J (Anniversary) - SACHS RACE ENGINEERING COIL OVERS
    225/40 R18
    I always fitted Dunlop MAXX RT AO, but recently switched to Pirelli P Zero SC AO XL.
    Running the Dunlops at the recommended 2.0 bar resulted in fairly even wear across the front tread.
    With the Pirelli tyres at 2 bar both front tyres are each showing massive wear on both shoulders.
    Of course this is an indication of 'Under Inflation'.
    I spotted it too late to experiment with higher pressures.

    Front wheel alignment is perfect.
    It has just passed the NCT so there is no wear in the front suspension.

    So.
    Has anyone else seen this phenomenon with other tyres?
    Is 2.0 bar front too low for the 25J? (My son's Mk5 ED30, with the same size tyres runs, 2.6 bar at the front but it is a chubby 78+ kg heavier then the 25J)
    The 25J is not supported very well with data.
    For example:
    The standard car is lower than any other Mk4 but neither the VW dealer nor I can find a figure for the correct ride height!
    Perhaps the tyres pressure for R18 wheels should be higher and, as with ride height, VW could not be arsed to do the job properly!?

    Any comments please.

    Regards,
    Dave.

    Interestingly. Mk5s run different pressures for identical cars with different size wheels.
    mk5 tp2.png


    PZERO.png
     
    Last edited: Dec 24, 2021
  2. Tristan Paid Member Paid Member

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    Hello sDad.

    I've a few car enthusiast friends working in the NCT, and they would tell you themselves, a pass doesn't mean suspension isn't worn, more that it's worn equally both sides.... They're more concerned about imbalance.

    However, I think it's a tire difference thing. Your new Pirellis just want more pressure than the Dunlops.
     
  3. Dave

    Dave Pedantic Old Fart Paid Member

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    Thanks my loverly sSon.

    You are obviously very correct!

    I have researched tyres pressures for Mk5 and Mk6 cars.
    I checked the weights and tyre sizes and have come to the following conclusion:

    The tyre pressure on the filler cap is wrong for the 25J!

    For the car weight and tyre size the pressure should be 2.6 bar!

    I believe that the wear was less obvious on the Dunlops because the construction of the sidewall and tread plies are stiffer than the Pirelli tyres.

    So. When new Pirellis are fitted to Elaine's 25J we will use 2.6 bar.

    I shall report on the results.

    Dave
     
  4. Tristan Paid Member Paid Member

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    I look forward to hearing from you.
     
  5. valvemiester

    valvemiester Paid Member Paid Member

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    I have a 2008 Octavia vrs estate 2.0 tdi as the everyday car with standard alloys on 225/40r18 92Y XL and have used michelin sport 3 and sport 4, uniroyal rainsport and Goodyear Eagle f1 all using the factory tyre pressures of 2.1 bar front and 2.2 bar rear with no abnormal tyre wear. I know it's not a golf but is a golf mk5 platform and dare I say it heavier than your mk4 being diesel and an estate as well.
     
  6. Tristan Paid Member Paid Member

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    Maybe so, but it's a completely different chassis.
     
  7. valvemiester

    valvemiester Paid Member Paid Member

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    Yes Dave also stated he had been looking at mk5 tyre pressures as well and an octavia shares the same PQ35 platform is common to both as well as the mk6 golf, hence my reply.
     
    Last edited: Dec 28, 2021

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