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Old 03-04-2014, 02:08 AM   #1
68C20 CST
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Tire Size for 68 C20 with 71 Disc Brake conversion

First off my tires are old and dry rotted and I need to get new ones. I want to get new wheels and tires but im not sure what size tires and wheel width/backspace I should go with. I want to stay with 16" wheels.

I have a 68 c20 with what I was told to be 71 disc brakes. I currently have 245/75r16 tires.

With a disc brake conversion the front wheel/tire track width is about 1-1.5 inches wider than the rear.

what is a good tire size/wheel width and backspacing to run in this situation? I am considering going a little bigger tire to 265/75r16's, the original tire size on the build sheet shows 950X16.5x8 which should be equivalent to around the 245/75r16's that are on it.

What would be the best way to get the track width closer from front to rear. Should i get new wheels with a wider backspacing on the rear than the front to make up for the track width difference or go with a wider wheel/tire in the rear than the front? what are others doing or what do you thing would work/look the best?
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Old 03-04-2014, 10:26 AM   #2
Sicklajoie
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Re: Tire Size for 68 C20 with 71 Disc Brake conversion

I run 16 x 7 F#rd van steel wheels which I believe have a 4.5" backspacing, on 265/75/16 tires.
As far as evening up the treadwidth, you could run 1/2" spacers on the back and still have the same rims all the way around. I don't know if you would need longer studs to clear them, or if it would affect your towing needs.
Great looking truck BTW!
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1970 C/20 - 402/TH400/3.54s - 74K miles
2003 GMC Sierra 2500 - Wheatland Yellow
Niner Progression Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=697183
Classic Trucks article: https://www.motortrend.com/features/...et-c20-driven/
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Old 03-04-2014, 08:16 PM   #3
airdale94
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Re: Tire Size for 68 C20 with 71 Disc Brake conversion

If you swap the rear with a Corp. 14 bolt out of a 73-87 that will get you even with the front. For what it's worth, 88-97 factory wheels have less backspacing and will put the wheels in the wheel wells about in the stock location. As far as I know all of the older wheels, all makes are 4.5" backspace. The 14 bolt rear also gives you better gear selection. Currently you can go down to 3.42 new, and 3.21 is a option but you have to find used.

Good looking truck! Mine is same color and a 68'.
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68' C20. 283CI w/55CC 305HO heads, NP435 Close Ratio, Corp. 14 bolt FF 3.21, 75' front end swap (everything but the X-member).

Last edited by airdale94; 03-04-2014 at 08:19 PM. Reason: add
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