Anyone running 10” wheels on ‘68-69 Skylark with trimmed fender lips?

Discussion in 'The Hides' started by STREETFIGHTER50, Jul 2, 2019.

  1. STREETFIGHTER50

    STREETFIGHTER50 Well-Known Member

    I’d like to get some new shoes for the Lark. Whats the best backspacing to go with on 17x10” or 18x10” wheels for the ‘68-69 years with the fender lips trimmed and rolled?

    I really like the stepped lip look. Here’s some pics of the wheels I’m interested in.

    Weld S77 (Available in 17x10”/5.40” BS and 18x10”/5.70” or 6.20” BS)
    https://www.weldwheels.com/product/weld-s77-wheels/

    This GTO has the Weld S77 wheels I want, but needs bigger tires, IMO.[​IMG]
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    This Chevelle has the Weld S71 wheels with the perfect size tires and stance all around IMO. Unfortunately Weld doesn’t list any specs of the cars pictured on their website :(
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    RocketRacing Attack (Available in 18x10”/5.00”, 5.50”, or 6.00” BS)
    http://www.rocketracingwheels.com/rocket-attack-hyper-shot/p679

    This Chevelle has a bad ass set up as well! Running 18x10” Rocket Attacks with fat 305’s!
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    Last edited: Aug 7, 2019
  2. BrianTrick

    BrianTrick Brian Trick

    If you have the factory rear drum brakes,you want a wheel with 5.5” backspace. If you are running an type of rear disc brake,you can get a 6” backspace. Take advantage of the room on the backside. You also want to stiffen up the rear suspension,as with any old car,to eliminate any excess bodyroll.
     
    STREETFIGHTER50 likes this.
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Everything I have read about 68-69 cars is they need more back spacing than the 70-72 cars. 5.5” is what the 70-72 cars need, maybe even 5.625”.
     
  4. BrianTrick

    BrianTrick Brian Trick

    It would still be the same backspace. However,since you are running a 17” rim,you could squeeze a 5.75” or 6.00” backspace and not hit the shock mount,due to the larger rim.
     
  5. STREETFIGHTER50

    STREETFIGHTER50 Well-Known Member

    Car has RideTech Coil-Over/MuscleBar and CPP Big Brake kits with the stock rebuilt rear end. Here’s some pics of the current set up with US-MAGS Standard U107 wheels in 18x8” 245/45 fronts and 18x9” 275/40 rears. The 9” rears have a 5.25” backspace which gives me an inch on both sides of the tire, a tiny bit more on the inside actually... So what’s the verdict y’all? :) What backspace should I go with on these available sizes/sets listed on the first post?

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    Last edited: Aug 7, 2019
  6. 87GN_70GS

    87GN_70GS Well-Known Member

    You currently have 0.25" offset and you state you have a little more clearance to the inside than out. I might go with 0.50" offset, or 6.0" BS on a 10" wide wheel, or maybe 3/8" offset (5.875" bs)

    The 5.70 might be close enough
     
    Last edited: Aug 7, 2019
    STREETFIGHTER50 likes this.
  7. STREETFIGHTER50

    STREETFIGHTER50 Well-Known Member

    I know it’s just a few mm, but would you say the 6” BS wheel is the safer choice then? I plan to run 285/40 or 295/35
     
  8. 87GN_70GS

    87GN_70GS Well-Known Member

    That's a 1/2" offset which is .25" more than you have now. Check the new tire section width on that size wheel to compare with what you have now. Subtract that from your one inch inner and outer,then see if you can deal with .25" less to the inside from the increase in offset
     
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  9. STREETFIGHTER50

    STREETFIGHTER50 Well-Known Member

    Ok I think I’m gonna pull the trigger soon on the Weld S77 wheels. As for tires I’ll be going up one size front and rear.
    Front: 18x8 w/4.70 BS and 255/45-18
    Rear: 18x10 w/5.70 BS and 285/40-18
    It should be equivalent to the 18x9 with about .55 inch added to the outside and about .45 inch to inside. Thanks for the replies folks!
     
  10. 87GN_70GS

    87GN_70GS Well-Known Member

    By my estimations, you haven't lost as much as that. To the inside, the tight spot is the tire bulge (or section width) to the frame just ahead of the axle, on wheels larger than 15" (clears the lower shock mount). You lose 5mm section width, gain .050" from offset, and lose 1/4" due to the wheel bead being wider (bead is actually 1/2" wider to the inside, the tread a small amount, and at the bulge which is half way between the bead and tread, you lose about half the total bead increase). So I get you lose about .4" to the inside and have about .6" (or roughly 5/8") left over from your 1".

    To the outside, the tight spot is nearest the tread to the qtr lip. You lose 5mm tread (assume tread and section width are wider by the same amount), lose .050" from the offset, and 0 at the bulge (doesn't really hit to the outside unless you're super lowered). Or roughly lose .25" leaving you with approx .75" space to the outside.

    i get a dozen krispy kremes if im right to with 1/4" =D lol:)
     
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  11. STREETFIGHTER50

    STREETFIGHTER50 Well-Known Member

    Thanks Scott! If u were out my way we could cruise on over to Krispy Kreme’s. It’s like 2 miles from my house. I got u! :)
     
    jaye and 87GN_70GS like this.
  12. STREETFIGHTER50

    STREETFIGHTER50 Well-Known Member

    How about the front? I’d like to go 9” wide if possible. The current 18x8 has a 4.50” backspace. So would you say 18x9 with a 5.00” BS to be safe? It would add a 1/2” to the inside and 1/2” to the outside correct?

    Looks like plenty room up front.
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    87GN_70GS likes this.
  13. 87GN_70GS

    87GN_70GS Well-Known Member

    On my 70 i have 17 x 8 with 4.75" b.s. (.25 os). Tire diameter is really the culprit up front. 9s will fit as long as the tire isn't too tall. On mine, the tight spot to the outside is the top center inner fender screw. It can be removed, but with 26.6 tall tires it just kisses it on full suspension compression and squashing the lower rubber snubber a little. To the inside, when the steering wheel is full lock, the outer edge of the tire, at the rear, just barely, ever so slightly brushes one inner fender. Loosening the fender bolts and massaging it has since cleared it up. Actually here, more backspace helps at both spots. There is plenty of clearance to the sway bar, the next closest interefernce spot, like 2"

    i would go 5.25 maybe on the front with a 9. But 5 bs is fine with a 26.5 or shorter tire

    Factory rally wheels were 1/4" offset front and rear.
     
  14. Jimbotron

    Jimbotron Member

    I'm interested in seeing the finished set up. I'm about to do the same on my '68 GS350. Please post your specifics.
    Thanks!
     
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  15. STREETFIGHTER50

    STREETFIGHTER50 Well-Known Member

    Ok I changed my mind on the Welds. I don’t wanna deal with the maintenance of polished aluminum with anodized centers. Also, they’re quite a bit more expensive than the RocketRacing wheels... So for the front end I can get Rockets in 18x9 with 5.00” or 5.50” backspace. Which would u go with Scott? :) Also, 255/45 or 255/40?
     
    Last edited: Aug 16, 2019
  16. 87GN_70GS

    87GN_70GS Well-Known Member

    Seems like 1/4" offset is the sweet spot for your setup on the rear, but since you now want a little narrower tire and wheel, either 5 or 5.5 should be fine.

    You could always get the 5.5 bs and run a 1/4" spacer, but I don't know how you feel about spacers.

    I would be tempted to go with 5.0 bs, as it gives a little more clearance to the top inside of the tire on hard cornering as the rear rotates upward.

    I would run 255/45 rear and 255/40 front
     
  17. STREETFIGHTER50

    STREETFIGHTER50 Well-Known Member

    Ummm wait a minute, I’m going wider front and rear, not narrower :( That last post I should’ve made clear was about the front end only lol :) Let me correct it. I would like 18x10” 285/40 rears and 18x9” 255/40 front if possible.
     
    Last edited: Aug 16, 2019
  18. 87GN_70GS

    87GN_70GS Well-Known Member

    Sorry, I misunderstood. For the front, 255/40 and 18 x 9 with either bs would be fine, I would pick 5.5
     
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  19. Sebambam

    Sebambam Well-Known Member

    I run 19s since years
    19x8.5 upfront
    19x10 in the back
    Pro touring dont have to be expensive, just look outside box sometimes
     

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