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Thread: Offset Question

  1. #1
    Registered User texasz's Avatar
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    Default Offset Question

    On a wheel that has a +42 offset as I understand it you need a spacer for this wheel to fit on a 240Z. Question is would the spacer need to be a -42?


    A + offset means the wheel where it attaches to the car is further from the car where as a - offset it is closer. Right?
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    '71 240Z - HLS30-018482 - Production Date 1/71,Corvette Yellow, driven under a 4Runner, bought for parts, hit lotto with parts on car, may fix and put back on road

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    Supporting Member ChrisA's Avatar
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    Default

    I think my spacers are 40 mm thick to mount my 40mm offset wheels.
    1973 240Z HLS30-156693

  3. #3
    the QuackWacker GunnerRob's Avatar
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    Hi texasz,

    Here's a page from TireRacks web site that'll explain what an offset is.

    http://www.tirerack.com/wheels/tech/offset.htm

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    Registered User alien-e's Avatar
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    Default

    Then my quesiton is, where is the stock mounting point on my 240Z? Is it at zero offset inside the wheel housing, or (+) some milimeters?

    I'm buying the adapters from Modern Motorsports, but they are very vague about how thick the adapter is. When I asked, I got this response:

    "The adaptors suitable for wheels ranging from 36 to 40mm offset as described (range of 0.15", not much) are of one geometry only. So if your's fit the recommended offsets and widths you'll be just fine with our typical adaptors. Custom adaptors we can do separately but sounds like you're fine with our typical adaptors."

    When I pressed the issue they admited that the adapters are 1.1", which converts to 27.94 millimeters. How is this going to fit a 40mm offset rim?
    Alien-E : 1973 240Z

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    Registered User alien-e's Avatar
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    Default

    On a side note, why are they using standard measurements when offset is traditionally in metric? Especially for a Japanese built car. I'm pretty sure these guys are Canadian, and their whole country standardized on the metric system. I'm boggled.
    Alien-E : 1973 240Z

  6. #6
    Registered User alien-e's Avatar
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    Default Modern Motorsports link

    Thougt it would be helpful to add a link to the product I'm talking about. Z to Honda Wheel Adaptors
    Alien-E : 1973 240Z

  7. #7
    Registered User Victor Laury's Avatar
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    For 14 and 15 by 7 inch wide wheel on a 240Z, offset of 0 to +15mm is best fitment. that means the mounting plane (that rests against the hub surface) is dead center in the middle of the wheel (for a 0 offset) or 15mm outboard (moving the wheel center inboard). The Hondas, and most FWD cars, use a 35~40 offset. If you tried to use this wheel on the Z, the back of the tire would be hard against the strut tower. To change a +35mm wheel to 0 offset, you would need a spacer 35mm thick. If you put a 35mm spacer on a +40 wheel, it would be effectivly a +15 wheel when you finished.

    By the way, on 16 and over wheels, a +15 offset is optimal as a 0 will rub the outer fenders on bumps. So if you bought some 17X7 +40 4X100 SSR's, the spacer offered by Modern Motorsports would be just about perfect.
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    Originally posted by Victor Laury
    ........ If you put a 35mm spacer or a +40 wheel, it would be effectivly a +15 wheel when you finished.
    ? ? ? I'm lost here.

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    Registered User alien-e's Avatar
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    I think I understand. I was planning on on a set of 15 x 6.5 +40 4X100 Nippon Racing F2's (12 pound alloy wheel). So, if I follow the logic, the offest would be +12.06MM with the adaptor. I might consider getting a 7" rim, to fill out the wheel wells with a slightly wider tire.

    Thanks for the help Victor.
    Alien-E : 1973 240Z

  10. #10
    Registered User Victor Laury's Avatar
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    Originally posted by Bambikiller240
    ? ? ? I'm lost here.
    I misspelt. My bad. it was suppose to read
    "If you put a 35mm spacer on a +40 wheel, it would be effectivly a +15 wheel when you finished."

    Instead of "or"
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    Originally posted by Victor Laury
    I misspelt. My bad. it was suppose to read
    "If you put a 35mm spacer on a +40 wheel, it would be effectivly a +15 wheel when you finished."

    Instead of "or"
    Yes, I figured that part out. What confuses me is :

    "To change a +35mm wheel to 0 offset, you would need a spacer 35mm thick." I think I understand it this far. 35mm offset wheel, 35mm spacer to put back in ZERO offset place.

    BUT Then, "If you put a 35mm spacer on a +40 wheel, it would be effectivly a +15 wheel when you finished."
    Following the first example, I'd have thought the wheel would be effectively a +5 wheel. 40 - 35 = 5 ? This is where I get lost.

  12. #12
    Registered User Victor Laury's Avatar
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    Well you Can't expect me to actually do rithmatic, do you? You know I aint got 40 fingers and toes! I know some. The adds and the takes-a-ways and even some of the gizindas (4 gizinda 8, 2 times). I'd know more but, in school, Elle-May Clampet was always wisperin in my ear bout the swimin hole. Makes it hard fer a man to think bout anything except multiplication.
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    Gazintas, I remember those thangs! I understand about Elle-May Clampett. There was an Elle-May in my math class also. Thank goodness for calculators!

    Though maybe it had to do with the +15 offset mentioned in the 2nd paragraph (about 16" wheels) or something. I get really lost on this offset stuff (all on my own) then different people explain it different ways, and some folks get + offset and - offset confused when they discuss. John Coffey had me spinning in circles one day.

  14. #14
    Registered User tanny's Avatar
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    I have been looking at wheels on Ebay and was also a bit confused about offset for a bit. Apparently, the more positive offset you have, the more the rim moves toward the inside of the wheel well. Unless I'm still confused. Also, I think I saw somewhere that most fwd cars are in the +40 range, and rwd cars are around 0 to +15. Please correct if my memory has failed as usual. Victor.
    73 Z, 06 Honda civic

  15. #15
    Registered User Victor Laury's Avatar
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    No correction needed Tanny. You got it right the first time.
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  16. #16
    Registered User 75BlackZ's Avatar
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    OKAY.. OLD thread.. but why start a new one?

    I want to put 42 offset wheels on my car.... so i needa put in a 42 spacer in??

    If I can only find a 40 offset spacer... will the +2 be a big deal? How much offset left over can can be considered "okay"?

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