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Wheel Fitment Guide

Discussion in 'Wheels / Tires / Brakes' started by GP403, Sep 7, 2007.

  1. GP403

    GP403 Administrator
    Staff Member Site Admin Moderator

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    This post to create a standard "guide" for wheel fitment. What I need from you guys is the following information, just reply to this post and I'll update this entry with the correct information...

    - Factory Lug spacing
    - Factory back spacing
    - max/min Backspacing that will work in an unmodified A/G wheel well, front and back
    - max wheel/tire width and diameter that will work.

    Not looking for anything that involves modifying the body or suspension, just some facts on what will fit "as is." This is a topic that keeps coming up, and with a proper guide maybe we can avoid a lot of repeat questions... Thanks!

    Revisions
    ---------
    2007-09-07 - Initial Post[/list]
     
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  2. 85t5mcss

    85t5mcss Master Mechanic

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    Factory Lug Spacing on all 78-88 A/G Bodies is 5 on 4.75"
    Factory wheels are 14x6 and 15x7. 14x6 BS is ???, 15x7 BS is 3.75"
    14x6 wheels run a factory tire size of 195-70-14 which is a 24.8" OD tire.
    15x7 wheels run a factory tire size of 215-65-15 which is a 26" OD tire.
    78-81 use 7/16"x20tpi lug nuts
    82-88 use 12mmx1.5mm thread pitch

    I currently run a 17x8 with 4" BS.
    Tires are 255-45-17 and lowered 3". It only rubs at full lock because of the extra lowering.
     
  3. 85 Cutlass Brougham

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    Car: 1985 Cutlass Supreme Brougham

    Wheels: Enkei #92
    Size: 16x8
    Backspacing:4 in
    Tires: 245 50 16
    Fitment issues: front rubs at top of wheelwell when suspension is under full compression, rubs inner fender at full lock. Also, the car is sensitive to what brand/model of tire is used. Some are wider than others. BFG T/A's fit better than Goodyear Eagle GSC for example. Check to be sure the body is square on the frame. Some cars are offset by up to 1/4 in and it makes it rub worse on one side. My car's mods to the suspension include: Eibach lowering springs, rolled front fender lips/removal of some of the inner fender at the top of the wheelhouse, F car steering box from an IROC-Z, FE-2 swaybars. However, I did run these wheels/tires with the stock suspension before the V6 was swapped out.

    I'll also add that it is important that people post the year/model G body they have.There are slight differences between the bodies that can cause problems with some that do not exist in the others.
     
  4. Tony_SS

    Tony_SS Royal Smart Person

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    Location:
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    79 Monte

    FRONT: 17x8 - 3.5"bs 245/45
    REAR: 17x9.5 - 4.5"bs 285/40

    Suspension:
    Eibach Lowering Springs (soon to be changed - not enough drop)

    I used this calc to determine tire fitment:
    http://www.miata.net/garage/tirecalc.html
     
  5. Sprottrod

    Sprottrod Not-quite-so-new-guy

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    I have 79 malibu I have 15x8 Weld Pro Stars on back. Dont know BS, but I have 28.5 tall and 8 wide ET streets on them. They fill up wheel well good and have never rubbed
     
  6. v8power

    v8power G-Body Guru

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    you should post some pics of that bad boy up on here, from the movie, it looks like a really bad ass car!
     
  7. JDub

    JDub Apprentice

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    how do you like the eibach lowering springs? i went to there website, and the only kit they offer only lowers 1' in the front, and 0.8' in the back. i think i need a little more drop than that. the site also doesnt give a price. how much did you have to pay?
     
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  8. kingcolbert83

    kingcolbert83 G-Body Guru

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    78 buick regal on original painted black rally wheels

    235/60/14 Front
    255/70/15 Rear with adjustable air shocks.

    Will probably upgrade to 275 next time i get some tires for the back

    But does anybody know or can the figure out the max bs for the rally wheels. There is a guy on ebay that custom makes them with your specs on backspacing. I want the deepest dish in the back with the originals but dont want to order if they arent going to fit.

    http://cgi.ebay.com/ebaymotors/BUICK-RA ... 0232249944
     
  9. Tony_SS

    Tony_SS Royal Smart Person

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    Yeah, don't bother, I'm switching them out.
     
  10. Lawfree

    Lawfree Not-quite-so-new-guy

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    I'm real interested in what you were able to do to the FRT. wheelwells to gain more clearance. I have an 80" Cutlass Calais, with new 15" Outlaw II and 60 series rubber, the tire would make severe contact with the top of the plastic fenderliner even with 1'' spacer blocks under the stk. F-41 springs and new HD shocks. The dealer took the 15's back and installed 14s. I am installing Moog 5660 S10 Springs and Edelbrock shocks along with the S10 Extreme new design bumpstops. I hope then to be able to run 15" wheels with out interference. I picked up a pair of 2003 Blazer knuckle/hub/rotor/dp calipers and I know I will need bigger wheels (not knowing what came stock on the Blazer).
     
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