10.5 Slick 68-69 Skylark

Discussion in 'Street/strip 400/430/455' started by Skylard, Jun 22, 2021.

  1. Max Damage

    Max Damage I'm working on it!

    Corners! Stop the crazy talk.
     
  2. Bens99gtp

    Bens99gtp Well-Known Member

    By corner I ment turning at the end of the drag strip, getting around the pits, etc
     
    70 GMuscle and Max Damage like this.
  3. BrianTrick

    BrianTrick Brian Trick

    A 275/60/15 will easily fit. The pictures I posted earlier are a 15x10 rim with 5.5” backspace and a 325/50/15,which somewhat dwarfs a 275/60/15.
    A 275/60/15 would also work better on an 8” or 9” rim.
     
  4. LARRY70GS

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

    As long as you have the clearance, there is no down sides to more back spacing. Right now, my regular 275's fit, both regular tire and Drag Radial, they are just VERY close on the driver's side only. I remedied that recently by shimming up the bottom of each spring to increase my rear ride height. Before that, it would rub on big bumps. At the track, the no hop bars actually push the rear down and the back of the car rises on launch, so never a rub problem. For me, all I need is 1/2" more back spacing and that will remedy my problem completely.

    Yes, an 8" rim is actually 9" edge to edge, so 4 1/2" back spacing is actually ZERO offset. More back spacing gives you more positive offset, which lots of cars seem to need. In one of the earlier posts in this thread, I said 5.5" back space is bare minimum, on a 70-72 car, for a 10" wide wheel, which is actually 11" edge to edge, so 5.5" is again, ZERO offset. I know the 68-69 and earlier cars need even more in some cases.

    Let us know how it works out for you.
     
  5. 70 GMuscle

    70 GMuscle Plan B

    That’s a fantastic set up. I’ve seen a couple generations of it. My friend has 2 sets. Look forward to him getting his cars done.
    I went w HR for street use. Been using it over 15 years. Need to get car back on street tho now.
     
  6. Canadian GS 350

    Canadian GS 350 Well-Known Member

    Larry, Brian, I’m sure my 72 gs is the same as all the 70-72’s out there. With rear wheels off the car, jack stands under rear simulating loaded ride height suspension, I have 7.25 inches from drum face to frame, 5.75 inches from drum face to edge of wheel well moulding. Both sides are the same plus or minus a 1/16 of an inch. So rear is very well centered under the body. So to optimize a 10 inch rim, which is 11 inches wide, a 5.5 inch back space is far from optimum. 6 inch is much better, on my vehicle, maybe 6.25 would center the rim perfectly. Of course these back spacing s are probably only available on custom basis. Unless you want to jack your car up with air shocks, or run heavy rear springs and trim wheel well moulding or roll lips, then I guess 5.5 back spacing is ok. But 5.5 is not a great choice on a 10 inch rim if 6 inch is available and you don’t want tire rubbing issues.
     
  7. LARRY70GS

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

    I know, I just ordered two 15 X 8" Buick Rallye wheels from Wheel Vintiques with 5" (custom) back spacing. They said August 6th. I hope that is accurate.
     
  8. BrianTrick

    BrianTrick Brian Trick

    You have a 275/60 tire stretched on a 10” rim. That would more effective on an 8 or 9” rim.
    Is there room between the bead of the rim and the frame? Absolutely. The problem is that most tires will bulge out beyond the bead of the rim,and the sidewall of the tire is where you will have the minimum clearance. That is what will hit first. A 5.75” backspace would be ideal,but that backspace is not available unless custom-made. 6” is too deep. No,the rim itself won’t hit,but most tires will. The only thing the rim will hit is the shock stud,unless you have moved them inboard,or have an aftermarket housing,like Moser,that has them in behind the lower control arm,where they should be,to take some angle off the shock and let it work better for 60fts.
    For those of you that have 3” tail pipes tucked all the way to the bumper,you will run into clearance problems with the side of the tread,and the pipe,once you get to 5.5” backspace or deeper. Most people don’t have them tucked up where you can’t see them,but I do,and that makes a clearance issue with wiider tires and deeper backspaces. I have taken that section of the tails and made them oval,to gain tire clearance. I have recently put 3.5” tails on another car,and I modified the back of the frame to gain some more room. It can be done.
     
  9. Canadian GS 350

    Canadian GS 350 Well-Known Member

    Brian, here are a couple pics of a 295/50/15 with 6 inch back spacing - these are on a site members car. No clearance issues at all.

    Were just not going to agree on this, so too each his own. B19D90B2-A004-4F01-8CDD-045E7241B41D.jpeg F10856B7-EB2F-46B1-AAB2-F6FAB99AD854.jpeg 05B20341-67B6-4330-A52B-9278BEA79BEB.jpeg

    Fyi - the 275/60/15 MT drag radial Pros ive been talking about are much larger than a standard 275. 12.5 inches at cross section, 10 inches plus of surface contact. Which is ideal on a 10 inch rim. A 6 inch BS would have allowed the tire to work. 5.5 is just not the best choice.
     
  10. BrianTrick

    BrianTrick Brian Trick

    My 325/50/15 is still bigger than that 295/50. I guess that’s my point. If you took my wheel and put it under your car,you would see what I’m talking about. You can’t go any further,either way. It is centered and squeezed up in there with zero modifications to the body. A 275/60 gives me a bunch of room.
     
  11. sean Buick 76

    sean Buick 76 Buick Nut

    I’ve also had good results with 5.5” backspacing with a 15x10 and NO trimming it easily fit 15x10 with 275/55R15 and also 285/70R15 no rubbing at any speeds. Perfect fit:


     
    Last edited: Jun 28, 2021
  12. BrianTrick

    BrianTrick Brian Trick

    Another thing to mention is if you have rear discs. The rotor hats are thicker than a drum,so that will push the wheel out 1/4”-1/2” depending on brand of kit.
     
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  13. 70 GMuscle

    70 GMuscle Plan B

    No 2 cars are alike.
    You can buy 8,9 or 10” wheels to fit your car.
    And back spacing in 1/8” increments from holeshot.
    Great quality company.
     
  14. Bens99gtp

    Bens99gtp Well-Known Member

    Im.sure they are great products.....but at 500+a wheel is outside of what I can afford
     
  15. Sebambam

    Sebambam Well-Known Member

    i have 15x10 Welds with retro Dishes.
    BS 6; i relocated the lower shock mounts inside, i added longer studs and 1/4in Spacer. + you have to trim the lip with such a big tire.
    i have MT 28x10.5
    20210130_172713.jpg 20210629_080059.jpg 20210629_080026.jpg 20210629_080101.jpg
     
  16. LARRY70GS

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

    What's the best way to do that? Does it involve a torch?
     
  17. BrianTrick

    BrianTrick Brian Trick

    No torches
    Depending on supply of tools,anything ranging from a rubber mallet to a block of wood and a harder mallet or get fancy and do it in a press. All have proven to be effective.
     
  18. Skylard

    Skylard Well-Known Member

    thanks for the info on the 68/69, i'll trim the lip and measure carefully before ordering wheels.
    I like the Retro look you created..
     
  19. Skylard

    Skylard Well-Known Member

    i just put 275/60's on 8" rim and there is 1" between the frame and tire, also tire to wheel-well lip is 7/8"
     
  20. Sebambam

    Sebambam Well-Known Member

    Go big or go home ...
    8" are fine but 10s are 10s lol.
     

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