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Discussion Starter #1
I'm restoring my 68 Convertible and I have some 15X8 Corvette rally wheels that I want to use. What size tires can I use that will not rub?
Thanks!
 

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I've had 275/60 BFG radial T/As on a 15x8 wheel with 4.5 bs on my 67. It was stock ride height and did not rub. They definitely filled the fender wells though. If you dont want the height of the 275 go with a 255/60. About the same width of a 275 but an inch or so shorter.
 

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What backspacing are the 15x8's? Are they real GM or reproduction wheels? Reproductions are available in 4"-6" backspacing. Are you wanting to put the same size tires front and rear?
 

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Sorry but the height is determined by the 60 series the width is you 275. I went through this on my 68. I'm running 17's in front and 18's at the rear. My 68 had 14" with F70x14s from factory. :)
 

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Sorry but the height is determined by the 60 series the width is you 275. I went through this on my 68. I'm running 17's in front and 18's at the rear. My 68 had 14" with F70x14s from factory. :)
That's not entirely accurate. The 60 determines the height of the sidewall as a percentage of the width of the tire. The sidewall is going to be 60% of the tire width.

So a 275/60 tire will be taller than a 255/60.
 

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That's not entirely accurate. The 60 determines the height of the sidewall as a percentage of the width of the tire. The sidewall is going to be 60% of the tire width.

So a 275/60 tire will be taller than a 255/60.
X2 on Brent's response.
 

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That's not entirely accurate. The 60 determines the height of the sidewall as a percentage of the width of the tire. The sidewall is going to be 60% of the tire width.

So a 275/60 tire will be taller than a 255/60.
X2 on the percentage of the width!
 

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Discussion Starter #8
They are GM wheels, not repros. Not sure of the bs. I will have to measure. I was hoping to use same tires all around unless that will look bad.
Anyone have any photos of this?
 

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The 15x8 up front would be the most critical, you would want 4.75" backspacing to center the tread in the space you have. I know one of the more popular same size all around is a 235/60 15 on 15x7 w/4.25" bs. If you have 4.75" bs on your 8" wheels it would be a good choice. since you have a '68 you might get away with a bit less back spacing but the tire might protrude out beyond the fender lip a bit depending on size chosen.
 

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The 15x8 up front would be the most critical, you would want 4.75" backspacing to center the tread in the space you have.
Just a comment. On my drum brake equipped 67 the distance from the drum brake mounting surface to the tie rod is 4.8"
I guess a disc brake car will have approx 5.3" clearance.
In my case 235/45-17 on 17x8 rims with 4.5" BS will clear the tie rod with 5/16"
 

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every one may have a different experience but this is mine. Factory Rallys have 4" back spacing. I have 15x8 Corvette Rallys on my 67. 21560r/15 bfg on the front. they do rub when you go through or over a bump. I put some Koni's and Hotchkis springs on and they seldom rub. But the 215's will look silly on the back. I have 255/60's on the back. trimed about 1/8" of the wheel well and they fit pretty good.
Phase two: i am putting disc brakes on the front which set the wheels out another 7/16" or so which is now too far for factory rally's. I ordered 5" backspacing 8" wide rallys by Wheel Vintiques from Jegs for $82.00 each free shipping. So far they clear the a-arm and tie rod. Ordering 2 more for the back. Lots of clearance and it looks good. Summit has them for $78.00. For the price you can't clean up and paint old ones.
 

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Brent MHO I was misinformed regarding the sidewall issue. That certainly does make more sense. Thanx :)
 

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Discussion Starter #15
every one may have a different experience but this is mine. Factory Rallys have 4" back spacing. I have 15x8 Corvette Rallys on my 67. 21560r/15 bfg on the front. they do rub when you go through or over a bump. I put some Koni's and Hotchkis springs on and they seldom rub. But the 215's will look silly on the back. I have 255/60's on the back. trimed about 1/8" of the wheel well and they fit pretty good.
Phase two: i am putting disc brakes on the front which set the wheels out another 7/16" or so which is now too far for factory rally's. I ordered 5" backspacing 8" wide rallys by Wheel Vintiques from Jegs for $82.00 each free shipping. So far they clear the a-arm and tie rod. Ordering 2 more for the back. Lots of clearance and it looks good. Summit has them for $78.00. For the price you can't clean up and paint old ones.
I looked on Jegg's page for the wheels you mentioned but I do not see them.. Are they GM type rally wheels?
 

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Discussion Starter #17
Well after measuring it seems I have non-factory Corvette rallys 15 X 8s with 4.25 backspacing. Honestly I can't tell if they are factory or not..kind of light but show lots of wear and pits...
I measured inside the backside of the rim from the flat surface (between lug holes) out to the outer lip...

So now I am wondering if can can use these or if I have to buy some 15 X 7s...
 

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Factory wheels will have a stamped code by the valve stem hole, however I'm not aware of a factory 15x8 with 4.25" bs. You can use them, depending the tire size and suspension set-up.
 

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Factory wheels will have a stamped code by the valve stem hole, however I'm not aware of a factory 15x8 with 4.25" bs. You can use them, depending the tire size and suspension set-up.
Thanks Garth,
I'll be running standard rear end suspension with multileaf springs and front springs with tubular A arms with disc brakes up front....
 

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I'm running stock 15x7 rally wheels with 245-60-15 radials, and rarely have a problem with any rubbing, front or rear. However, I am running drum brakes on the front, and now you all have me wondering if I will have issues if I convert to disc brakes this winter. I would like to stick with a stock rally wheel on this car. What backspacing was available with the 15x7 factory wheels? Is there a chart on the net somewhere that shows rim width and BS for the different wheel codes?
 
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