uneven tyre wear front and back

Discussion in 'Wheels, Tyres, Brakes & Suspension' started by such01, Jun 6, 2017.

  1. such01

    such01 Hardcore MB Enthusiast

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    Joined:
    Jul 13, 2016
    Location:
    Garden of England
    Car:
    E350 CDI W212
    had a VHC done at MB today and their video showed uneven tyre wear front and back.

    Both fronts were wearing on the inside and outside section, by 3mm compared to the middle. They are pirelli p zero's 245/35/19's with 38psi

    The rears are 1.5mm less on the inside edge compared with the middle and outer, with 40 psi, 275/30/19 uniroyal R3's. Middle is 6mm

    I had a 4 wheel alignment done when the rears were fitted around 5k ago, at WIM with just a couple of minor adjustments.

    I was told the rears tend to wear faster on the inside due to the setup, but I am quite suprised with the wear on the front.

    Apart from another alignment, is there anything i should be checking?
    Thanks
     
  2. Badvgood

    Badvgood Member

    Messages:
    31
    Joined:
    Mar 11, 2017
    Car:
    ML63
    You could try a few more PSI in the front tyres to 'push' the middle / centre of the tread out a little more to counter act the wear on the edges.

    Vehicle geometry can go out quickly so maybe worth a recheck and look for wear in any suspension / steering components.

    You could ask whoever does your geo to set the rear with a little bit less negative camber so see if it can offset the rear tyre wear but 1.5mm wear on the inside rear is not uncommon on any RWD vehicle.
     
  3. OP
    OP
    such01

    such01 Hardcore MB Enthusiast

    Messages:
    344
    Joined:
    Jul 13, 2016
    Location:
    Garden of England
    Car:
    E350 CDI W212
    thanks, the recommended psi in front is 35, up to 39 psi fully loaded.

    not sure if i want to increase any more. The VHC did not show any suspension issues or otherwise.

    Perhaps i may drop the psi in the front and check?


    Thanks
     
  4. Badvgood

    Badvgood Member

    Messages:
    31
    Joined:
    Mar 11, 2017
    Car:
    ML63
    Dropping the front pressure would lead to the edges wearing more than the center.

    Think about it, the edges of the tread cannot expand much as they are held in place by the sidewall of the tyre.

    The centre section of the tread can be expanded outwards by additional pressure to the tyre.

    Also as the tyre rotates faster, centrifugal force will throw the centre of the tyre out more than the edges, again as the sidewalls restrict how much the edges can move.

    If you do more motorway miles (high speed so centrifugal force) that city miles only go up by 1 to 2 psi and see, if its more city miles than motorway then I would say 3 psi more and try for a few thousand miles.

    Getting the max tyre wear is not an exact science and its trial and error. The tyres would be safe to go over by many more psi than you are increasing by.

    Also a calibrated tyre gauge is a must, not the garage forecourt junk or a £4.99 from Halfords job.

    As for the VHC, they don't tend to check suspension items. They just get marked down as green. Even an MOT it pretty pore on suspension checks with shaker plates etc. You need a tech that knows that model of car inside out to look for the weak points in what may have worn in suspension. They know how to leaver and manipulate the suspension to look for worn bushes and additional play. Not just a grab the wheel and see if there is free play anywhere.

    A VHC is sold to the consumer as a 'duty of care item' - When all its really doing is looking for additional work for the garage on quick, easy to sell and do types of work with good profit margins. IE Tyres, brakes, exhausts, bulbs, wipers etc
     
  5. OP
    OP
    such01

    such01 Hardcore MB Enthusiast

    Messages:
    344
    Joined:
    Jul 13, 2016
    Location:
    Garden of England
    Car:
    E350 CDI W212
    thanks for your reply, I have increased the psi to 40 on the fronts, as thinking about it, it does make sense.

    I do mixed driving with 60/40 motorway split.

    I'll monitor and see how it goes.
    The car drives straight, stops straight and the steering wheel is aligned correctly. No noises coming from the front that I can hear, especially at low speed and speed bumps.

    Thanks
     
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