Offsets, Backspace, and other wheel info

Discussion in 'Tires / Wheels' started by Bennett, Sep 18, 2005.

  1. Bennett

    Bennett Active Member Administrator

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    Backspace to Offset Conversion Chart

    The table below is a quick reference for finding offset- pick the rim width and follow the row over to the backspace of your wheel.
    [​IMG]

    Bolt pattern or lug pattern or bolt circle is determined by the number of bolt holes and the bolt circle diameter.

    Hub Diameter or center bore is the hole at the center of the wheel.

    Rear spacing or back spacing is the distance from the backside of the wheel mounting pad to the outside of the rim flange.

    Offset: The distance from the centerline of the wheel to the mounting surface of the wheel.

    Negative offset: When the back of the bolt pad is closer to the inside of the wheel; when mounting surface is inboard of the rim centerline.

    Positive offset: When the back of the bolt pad is closer to the street side of the wheel; when the mounting surface is outboard of the rim centerline.

    Bead-Loc A device which captures the tire bead between it's flanges, usually secured by bolts to keep tire bead from dismounting. Usually used in dirt circle track or off road applications where low tire pressures are used and hitting ruts or other vehicles are common. Left: An example of a Bead-Loc wheel

    Info on Stock Wheels:

    Bolt Pattern: 5x4.5" or 5-114mm
    Backspace: 5.5" (might be a hair larger than this actually)
    Offset is 41mm ( I know the chart says 38, but I found 41 from a tire vendor that said the factory wheels are 41 )
    Wheel size is 16 x 7
    Stock Tire Size ranges, but 235/70R16 is most common.


    If anything seems wrong please correct me.

    Bennett
     
  2. Bonehead

    Bonehead Full Access Member

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    Cool, that chart will save me a bit of math in the future.
     
  3. kolesy

    kolesy New Member

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    Hey can some one explain that vhart to me up there for the backspacing? I dont really understand what all the numbers mean. I know my tire width and i have a stock '05 sport with some 245/75/16 mtr's on and at full turn the front rubs a bit on the sway bar. I was wondering how much backspacing i would need to stop this. the help would be appreciated cause a lift and new rims are in the near future! I hope! lol the wife just wrecked her car today so i dont know. thanks!
     
  4. dnm45227

    dnm45227 New Member

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    Man that stinks. Hope no one was hurt in the crash. Maybe she'll get a kj now?
     
  5. kolesy

    kolesy New Member

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    Yeah she wass alright and everything. her car was pretty beat up but still fixable per All-state. so she is still keepin that but dont worry im sure we can talk her into a KJ eventually!
     
  6. fouros

    fouros Full Access Member

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    anybody know if the backspace on the stock steel rims are different to the alloys?
     
  7. vansterdam

    vansterdam New Member

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  8. FSJ Ralph

    FSJ Ralph New Member

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    Any idea what the offset is for factory 17" rims?
     
  9. cpliberty04

    cpliberty04 New Member

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    I would like to make sure that I understand the Offset Conversion Chart correctly.

    If my stock wheel is 16x7 with 5.5 offset = 38
    The chart shows 16x8 with a 4.5 offset = 0

    Does this mean that the 8" rim with 4.5 offset will be no different than my 7" rim with a 5.5 offset? The new wheel will be in the same position as my factory wheel, just an inch wider correct?

    Thanks!
     
  10. cpliberty04

    cpliberty04 New Member

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    Never mind. Guess this was a stupid question. I've decided to go with 16" Renegade wheels, so I'm just replacing one stock wheel for another. No calculations necessary.
     
  11. MeatBag

    MeatBag New Member

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    I have two questions please:

    1. What's the axle hub diameter for 2003 Liberty?

    2. Is the stock offset +41 for all four 16x7 wheels, or are the rear wheels different?

    Thanks!
     
  12. Atrus

    Atrus Full Access Member

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    Answer to #2 is that all 4 are the same, to the best of my knowledge.
     
  13. Aapo

    Aapo Full Access Member

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    I'd like to know that too. I'm too lazy to get the tire off to measure =)
     
  14. LibertyOrDeath

    LibertyOrDeath Full Access Member

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    I have this same issue with the stock wheels. Will rims with 4.5 or 6.5 in of BS fix it. I am looking at the silver soft 8s and am guessing the 4.5 is the answer. I tried searching first but I am using my phone so its diffucult to use the search function.
     
  15. bigBlue

    bigBlue Full Access Member

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    I have the 17" alloy/chrome (whatever) rims. What are the stats on this rim. Cant find anyone who knows, not even the local Jeep Dealership (haha).
     
  16. jas32

    jas32 New Member

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    Response is about 4 months late but the specs, from what I can gather, are as follows:

    17" (diameter) x 7.5" (wide)
    Bolt pattern: 5 X 114.3mm (4.5")
    Hub Center Bore: 71.5mm

    Not sure about the offset but most likely it's the same as the 16" wheel at +41mm.
     
  17. Jo6pak

    Jo6pak Full Access Member

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    Wheel Spacers and Back Spacing

    This is most likely an obvious answer to a stupid question, but here goes.

    How do wheel spacers affect backspacing?
    Am I right to think that a 1.25" wheel spacer effectively increases the backspacing of the wheel the same amount.

    Example. If I use a wheel 7" wide wheel with 4" of backspacing (offset= 0)and add a 1.25" wheel spacer, would backspacing then equal 5.25" (offset= 32.)
     
  18. Moab

    Moab New Member

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    Great Stuff Bennet - thanks for the quick reference chart.
     
  19. tjkj2002

    tjkj2002 Full Access Member

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    You went backwards...................

    4" of BS then add a 1.25" spacer you will be effectivily at 2.75" of BS,pushing the wheel out farther.
     
  20. Jo6pak

    Jo6pak Full Access Member

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    ....:favorites68:
    Just when I thought I had this stuff all figured out

    now I'm really confused.
    :emotions122:
    If the "backside of the wheel mounting pad" is the center that mounts against the hub.
    The "oustide of the rim flange" is the curb side of the wheel.

    Doesn't the wheel spacer (between the hub and wheel) increase the distance?

    .........Maybe I'm just overthinking this....