Front wheel backspacing question

Discussion in 'The Hides' started by SkylarkGeorgia, Apr 14, 2018.

  1. SkylarkGeorgia

    SkylarkGeorgia Active Member

    Hi all,
    What is the minimum (optimal) backspacing for 15x7 and 15x8 wheels for front on a 72 skylark with 255/60r15 tires?
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    4 1/2" will work for both 7 and 8" wide wheels. The 15 X 7" came stock with 4 3/8"
     
  3. SkylarkGeorgia

    SkylarkGeorgia Active Member

    Will 7" with 4"bs and 255/60 tire rub?
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    It might on the outside.
     
  5. SkylarkGeorgia

    SkylarkGeorgia Active Member

    Too bad I'm planning to put 15x10 with 5.5bs in the back and thought 7 would be better in front so there's a difference between back and front but those wheels are 15x8 4.5bs and 15x7 with 4 which in both cases make up a 0 offset considering the lips and the mounting part is in the center so i thought 7s would work.
    Won't 8" in front look too deep and same with 10s in back?
     
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I don't think so. Lots of guys have used 8's in the front and rear. The 10's look great as well, but you are getting to the limit of what you can stick back there. There can be side to side differences depending on how the body sits on the frame. It isn't that uncommon.
     
  7. NZ GS 400

    NZ GS 400 Gold Level Contributor

    I don't mean to hijack the thread, but will these guidelines also apply to the 67 A body?
     
  8. Mart

    Mart '71 350 GS, almost stock

    Nothing worse than a nice car at a show with rub marks on some baloney tires with wheels that don't fit! :rolleyes:
     
    Last edited: Apr 14, 2018
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    No, early cars need MORE backspacing than the 70-72.
     
  10. NZ GS 400

    NZ GS 400 Gold Level Contributor

    hmm. yep. I thought so. The wheels I want only come with 4" backspacing. I am thinking that on an 8 inch rim, I am only going to be able to use 235/60/15. What do you think Larry? Or better use the 7" wheel?
     
  11. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    You will need 5”+ on an 8” wheel. 67 cars never came with 15 X 7’s only 14’s.
     
  12. NZ GS 400

    NZ GS 400 Gold Level Contributor

  13. SkylarkGeorgia

    SkylarkGeorgia Active Member

    What i meant was i had two options: 1. 15x10 back and 15x8 front and 2. 15x10 back and 15x7 front. And since i wanted the wide deep look in the back and not so deep in front i thought second option would do better. The problem is those wheels don't come with 4.5bs for 7s.
    These are the wheels btw: https://www.summitracing.com/search...ed-wheels/wheel-bolt-pattern-app/5-x-4-3-4-in
     
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I can't tell you for sure whether a 7" wide wheel with 4" of BS and a P255 tire will rub or not.
     
  15. SkylarkGeorgia

    SkylarkGeorgia Active Member

    If 8" wide wheel, which actually including lips is 9" wide, with a 4.5" bs puts a wheel in the center of the wheel well with 4.5" on each side and does not rub logically a 7" wide (8" including lips) with 4" bs should also put the wheel in the center with even less 4" on both sides and should not rub either. No?
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Yes, but stock 15 X 7" wheels had 4 3/8" BS for a reason. I don't want to rain on your parade:), I just want you to know, that I can't guarantee that a 255 tire won't rub. It's up to you to decide if you want to roll the dice and see.:rolleyes: Your choice.
     
  17. SkylarkGeorgia

    SkylarkGeorgia Active Member


    I see, but thanks for your time and attention i value your experience a lot.
    I'll let you know what I'll decide and post some pictures later.
     
  18. Doo Wop

    Doo Wop Where were you in '62?

    I gotta agre with the folks here, 255s are too much for your front end. I would hate to live with all that rubbing and scraping. That will happen for sure.
     
  19. dynaflow

    dynaflow shiftless...

    ...but it wasn't for fender clearance, that's a body design issue. It was about steering geometry. Backspace was to make tire centerline and steering axis inclination ground contact points as close as possible. A zero scrub radius was ideal for our cars. Offset should be changed by half width increase to maintain scrub radius. Unfortunately, clearance rears its ugly head...
     
  20. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    OK, but the point is the OP is asking if 4" BS will work with a 255 tire. I can't be sure, and I don't want to say yes unless I am sure. I'm not.:)

    I have 15 X 7" wheels on the front of my car with the stock BS. I run 255 tires as well, but I have a relatively fresh suspension. No tire rubbing at all.
     
    Last edited: Apr 16, 2018

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