Looking for fattest rear 18" tires to fit 72 Skylark

Discussion in 'The Hides' started by koosh, Apr 1, 2021.

  1. koosh

    koosh Well-Known Member

    If anyone has experience on what is fattest 18" tire to fit on rear of 72 Skylark, I appreciate your input!
     
  2. sean Buick 76

    sean Buick 76 Buick Nut

    Attached Files:

    Last edited: Apr 1, 2021
    breakinbuick11 likes this.
  3. koosh

    koosh Well-Known Member

  4. sean Buick 76

    sean Buick 76 Buick Nut

    Hi, sorry I was mixed up the second set is 295/40R18 on a 18x10.5 wheel
     
  5. koosh

    koosh Well-Known Member

    Ok....the wheel I picked out (us mags rambler) only goes to 9.5 wide, not sure if that 295 gonna fit. If you get a chance, what is the backspacing dimension on the rears? I assume everything fit inside the well with no rubbing?
     
  6. breakinbuick11

    breakinbuick11 Platinum Level Contributor

    Hey Koosh,

    Sean was posting other project cars from the site here. (If I remember correctly Sean’s car runs a much larger tire on a tubbed setup.)

    @Sebambam , do you remember your backspacing off hand? I know you were running a 9” rear so not sure if the axles are the same length as a stock 8.5” BOP.
     
  7. koosh

    koosh Well-Known Member

    Yikes! Ok, yea, I certainly am not tubbed....
     
  8. sean Buick 76

    sean Buick 76 Buick Nut

    Hi yes sorry for the confusion BreakinBuick is right neither of those cars are mine I was just posting pics and info from breakbuick and seabams cars to help.

    yes a 9.5” wheel is fine for a 295 no problem there.

    Lol being mini tubbed I’m fitting a 31x18.5-15 but I only go straight!
     

    Attached Files:

  9. koosh

    koosh Well-Known Member

    Ok, thanks
     
  10. breakinbuick11

    breakinbuick11 Platinum Level Contributor

    but that stance is undefeated!!
     
  11. koosh

    koosh Well-Known Member

    Sean.... would you know what backspacing I need for 18x9.5 or 18x10 rear wheels?
     
  12. sean Buick 76

    sean Buick 76 Buick Nut

    Yes a with a 10” width a 5.75” backspace centers the wheel in the wheel well. 5.5” is commonly used.
     
  13. koosh

    koosh Well-Known Member

    Ok, then in your opinion, with no mods or clearance issues, for rear of 72 skylark, 295/40/18's maybe the biggest to fit?
     
  14. sean Buick 76

    sean Buick 76 Buick Nut

    To be safe I would stick with a 295 yes. Keep in mind that some cars have the rear end not Centered perfectly causing less clearance on one side or the other.
     
  15. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Koosh,
    As Sean said, most cars have more room on one side than the other. There is no way to predict this for YOUR car, you have to measure. If you don't, Murphy's law says it will surely bite you in the butt.:)

    It matters not what size rim you are talking about, be it 14" or 20", the rim WIDTH determines the back spacing requirement. For the 70-72 Skylark/GS, a 10" wide rim requires 5 1/2- 5 5/8" of back spacing. When you go this wide, that is when the side to side differences in YOUR car become critical. I recommend you measure as accurately as possible from the drum mounting surface to the outer edge of the wheel well.
     
  16. koosh

    koosh Well-Known Member

    Sounds good appreciate your help!
    Now to move on to the fronts, lol....225/?/18? Backspacing?
     
  17. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Rim width.:)
     
  18. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Stock tire height is 26.6". Moving away from that in the rear changes your speedometer calibration , and final drive ratio.
     
  19. koosh

    koosh Well-Known Member

    Oops...18x8
     
  20. breakinbuick11

    breakinbuick11 Platinum Level Contributor

    I run a 275/35/18 on a 9” wheel in front with no rubbing. My aftermarket ridetech control arms do rub my steering arms, so they needed to be massaged for better steering clearance . I did have to remove the top bolt from my inner fender. Most 15” cars are running 235-245s. You can safely run a 245 or wider.
    B007CBA8-E73F-448B-988D-59DD9DE47A63.jpeg
     

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