Backspacing/offset?

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by nicks78camaro, May 25, 2012.

  1. nicks78camaro

    nicks78camaro Veteran Member

    838
    0
    Apr 3, 2010
    Pittsburgh
    What's the optimum backspacing and offset to run for a 1978 Camaro with 15x7" up front? I'm looking at getting the Centerline Competition Series Rev wheels

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    Also with a 275/60/15 tire, would you run a 15x8" or 15x10" wheel? Would a wider tire fit in the rear of a second gen without modifications?

    Also, does anyone have these wheels on a second gen (black car?)

    Thanks guys!
     
  2. The Champ

    The Champ Veteran Member

    3,017
    20
    Sep 14, 2000
    MN
    Factory BS on the 15x7" steel wheels was 4.25".

    Many members have 275/60/15's on their Camaros.
     
  3. nicks78camaro

    nicks78camaro Veteran Member

    838
    0
    Apr 3, 2010
    Pittsburgh
    Are they zero offset? also would the 275/60/15 work better on an 8" rim?

    Also, what is the widest tire that can fit on the rear with 15" diameter rim with no modifications?
     
  4. HyPer

    HyPer Veteran Member Lifetime Gold Member

    738
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    Mar 19, 2012
    Central Mississippi
    15x7 with 4.25 BS would be a +18mm offset. Most 275/60s are recommended for 7.5-8.5" rims. I've got a set on a roller at the moment, rims measure out at 7.5", they definitely give that old school "WIDE-60" look.
     
  5. nicks78camaro

    nicks78camaro Veteran Member

    838
    0
    Apr 3, 2010
    Pittsburgh
    Ok so the Centerlines come in 3.5, 4, and 4.5" backspacing.

    I was gonna get 15x7" front, and 15x8" rear.

    I know 4.5" backspacing for the rear, but what about the front? 4"?
     
  6. rchydzik

    rchydzik Veteran Member Lifetime Gold Member

    660
    0
    Nov 13, 1999
    Colbert, WA USA
    If you have a zero offset wheel, backspace will slightly larger than you expect due to the tire mounting lip (1/2 inch). For example, a 15x7 wheel with zero offset has a backspace of 4 inches.

    7/2 = 3.5 inches
    3.5 + 0.5 (tire mounting lip) = 4 inches backspacing

    If the factory backspace is 4.25 inches on a 15x7 wheel, it has an offset of 0.25 inches (6mm).

    Having said all that, I ran 15x7 (no offset, 4 in backspace) all the way around with 235/60R15 tires with no problems for years. I also ran 245/60R15 with no problems, but that size and rubbing can vary by car.
     
  7. Tokyo Torquer3

    Tokyo Torquer3 Veteran Member

    2,182
    0
    Oct 14, 2003
    NJ
    After my recent experience with the Cen*%line wheels. i would not go near that brand again. After 6 months back and forth with wheels that would not balance because of very bad run out, I kept sending them back and the replacements they sent were just as bad. I heard this is a well known problem with the brand. Moreover, while the faces where polished nice, the backsides were totally hideous with weld spatter and pits in the finish everywhere. I ordered through Summit and the pics I sent them were bad enough that they totally refunded my money and added some gift certificates to compensate for my exerience. I went with another brand and all is well now.
     
  8. nicks78camaro

    nicks78camaro Veteran Member

    838
    0
    Apr 3, 2010
    Pittsburgh
    ^oh wow that's news to me, thank you for the advice
     
  9. nicks78camaro

    nicks78camaro Veteran Member

    838
    0
    Apr 3, 2010
    Pittsburgh
    So are the Weld Magnums better than the Centerlines quality-wise?
     
  10. Tokyo Torquer3

    Tokyo Torquer3 Veteran Member

    2,182
    0
    Oct 14, 2003
    NJ
    Weld makes great wheels, they are not in the same league.
     

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