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Thread: Gen2 Tyre side wall increase

  1. #1
    Join Date
    Aug 2009
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    hunter valley
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    Default Gen2 Tyre side wall increase

    Has anyone noticed on there Gen2 going from 225/40/18 oem to 235/40/18 or 225/45/18, front tends to run wider and understeer more. I have put 235/40/18 on so the side wall is a bit more, i have better traction under throttle and braking. rear has improved grip but front washes out more, which you tend to notice understeer more. Anyone else noticed this?

  2. #2
    Join Date
    May 2009
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    Bathurst
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    42
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    1,930

    Default

    2 theories here.

    1. Different brand tyres have less lateral grip
    2.(and what causes most arguments) weight is spread over a larger area, so there is actually less weight per square inch placed on the tyre.

  3. #3
    Join Date
    Aug 2009
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    the strange part is.. why has grip increased in back with less weight? I dont disagree with u i know its fact.. im thinking tho more sidewall roll with taller side walls

    I can fix the back with - camber and toe adjustment which will help with understeer

  4. #4

    Default

    yep, id say its the sidewall roll, and that the tyre is actually a bit too big for a 7.5'' rim. i bet it would improve on a wider rim.

  5. #5
    Join Date
    Dec 2010
    Location
    Sunshine Coast, QLD
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    458

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    increase the rolling diameter will help forward/stopping traction. the larger diameter makes the contact patch slightly longer (headleads to taillights).

    i don't think and extra 4mm for sidewall will cause much effect to steering dynamics.

    but a 235mm wide tyre on a 7.5" rim may cause a slight bludge effect on the sidewall near the shoulder.

    also there are many other factors aswell that could be cause this issue. tyre pressures, alignment etc have not been mentioned.
    Last edited by projectrracing; 15-02-2012 at 07:30 PM.

  6. #6
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    hunter valley
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    I have 18x8.5's 10kg rims, standard rim is 10kg thought about wheel weight.Im runing +48 offset

  7. #7
    Join Date
    Dec 2010
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    Sunshine Coast, QLD
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    offset and wheel weight have little bearing on this issue. i'd be looking at wheel pressures and your alignment. did they change your alignment much when you fitted the new tyres? did you get new wheel at the same time as tyres?

  8. #8
    Join Date
    Aug 2009
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    hunter valley
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    No wheel alignment change. Wheels and tyres same time.

  9. #9
    Join Date
    Dec 2010
    Location
    Sunshine Coast, QLD
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    458

    Default

    Quote Originally Posted by luke 3mps View Post
    no wheel alignment change.
    bingo!!!

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