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Thread: Rim widths 18x8

  1. #1
    Join Date
    Aug 2009
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    hunter valley
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    Default Rim widths 18x8

    Hi everyone.
    i have a question concerning rim width and offset i do apoligize if this has been answered before. if im running 18x8 offset 48 235/40/18 tyres, would 18x8.5 offset 48 235/40/18 tyres sit any closer to the guard?

  2. #2

    Default

    yes, by .25"

  3. #3
    Join Date
    Aug 2009
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    hunter valley
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    6,403

    Default

    ok i know the offset is taken from the edge of the rim to the hub but wasnt sure how it applied wanted to clairify. thanks again 2xs..

  4. #4
    Join Date
    Jan 2010
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    QLD - Brizzy Southside FTW!
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    1,031

    Default

    Yeah i'd like someone to clarify too... I'm currently looking at set of JDM spec rims but i wasn't too sure what was the best offset (45, 48 or 50mm) to go with abit of dish as i didn't want to roll my guards. Just so you know, Gen2 stock offset is 52.5mm and i've had Mazda Aust confirm it already lol I think i might still stick to the 7.5 rather than a 8 or a 8.5 although i reckon it would definitely handle heaps better but might cause some rubbing??

  5. #5

    Default

    Ok,

    Offset is calculated from the centre of the rim (width ways) to the back edge of the mounting face (the part that contacts the brake rotor)

    8" wide is 200mm, halfway would be 100mm

    +50 means +50mm offset from centre, outwards

    Therefore the back face would be 50mm closer to the front face

    +35mm would mean that the face is only +35mm closer to the outside/front of the rim and therefore sit further out on the car.

    To get more dish, you need less + offset, or a different style of rim.



    I've found that my car handle better with wider rims (7" std to 8" now) using the std tyres
    Last edited by 2XS; 16-05-2010 at 08:34 AM.
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  6. #6
    Join Date
    May 2010
    Location
    London, England
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    41

    Default

    Have I missed something here ??

    The OP asked that if he went up from 8 to 8.5 rims with the ET staying the same, with the 235/40/18 rubber also staying the same would the tyre get any closer to the guard, surely it would not, in fact because it was getting slightly "stretched" (yes I know it would be minimal, if at all) the tyre could actually sit very slightly further away.

  7. #7

    Default

    Quote Originally Posted by 07MPS6 View Post
    Have I missed something here ??

    The OP asked that if he went up from 8 to 8.5 rims with the ET staying the same, with the 235/40/18 rubber also staying the same would the tyre get any closer to the guard, surely it would not, in fact because it was getting slightly "stretched" (yes I know it would be minimal, if at all) the tyre could actually sit very slightly further away.
    Post number 2?

    The tyre at the point of the rim would be .25" closer, but as you said, the tyre may not actually get closer at the tread.

    If it is close now, is it worth the risk?
    Achievements
    2009 Jamboree Street Compact Winner
    Aust. Quickest and Fastest MPS
    12.3 seconds @ 111Mph.
    Proven over the Qtr mile

    Another Mazda 3 MPS - Almost fully bolted - Waiting for a turbo upgrade - The weekend hack.
    Toyota Yaris - Coilovers, rollcage, raceseats, harnesses, 18s - Also waiting for a turbo upgrade.
    2011 AWD Territory - White and Slightly lowered on 22s - The tow car.
    2011 RWD Territory - Black on black and slammed on 22s - The family transporter.

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