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#1 |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Got Cragars, will this backspacing work or do I need to exchange?
My mom bought me a beautiful set of Cragars from a car show she attended with my dad. They took about two months to arrive. They bought two 15x8's and two 15x10's. These are pretty standard sizes for these trucks, and everyone says this size will work. However, the wheels came with a backspacing that is a bit off.
If anyone could tell me what "OS" and "CB" mean that'd be great too.. The 15x8's have same Backspacing/"CB" however have a "OS" of -6. 15x10 have "OS" of -32 Incase this website decides to flip the photos around for me, I'll post the information as given on the 15X10 box. CRAGAR 61C515042 15x10.00 5/5.00 S/S Chrome 362 OS=-32 BS=4.250 CB=3.579 IF this backspacing is going to be alright, will it work with a 295/50/15 on the rear and 255/60/15 on the front? Thanks for the help, guys!
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD Last edited by HunterRotten; 01-04-2017 at 06:51 PM. Reason: added tire info |
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#2 |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Oh geez.. the rotation is very disorienting. They're not flipped around like that on my phone or my computer...
Here is an album with photos large enough to actually see things and flipped correctly.
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD |
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#3 |
67-72 parts collector,…
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Location: Mid-MO
Posts: 22,698
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Here's an offset to "backspace conversion chart".
I usually talk in Backspace numbers. OS= offset BS= backspacing I'm not sure what CB is??? Your backspacing is DIRECTLY related to wheel width. So the -32 on the 15x10's equals 4.5" of backspacing. (even though this chart says4.25" backspacing) On the 15x8's you have a -6 which equals a 4.25" backspacing. But since you already have the wheels,... flip them over "face side down", and measure the backspacing yourself. (from the wheel mounting surface, up to the edge of the rim) Easily done with a tape measure and a straight edge across the wheel. The amount of wheel backspacing is normally "personal" preference on how they look on the truck. But with 15" wheels up front that 4.25" backspacing is going to put the wheel lip really close to the lower control arm. (in the lower balljoint area) This might require you to trim the lip off the a-arm to clear the wheel. The 15x10's don't look like they tuck inside your fender lip,... but I don't know how low your truck is. Typically all these questions are asked prior to buying wheels.
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Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823 Last edited by lolife99; 01-04-2017 at 06:50 PM. |
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#4 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,455
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Re: Got Cragars, will this backspacing work or do I need to exchange?
There gonna stick out a little bit it not bad. If ur truck is slammed might be close, but I'd think you'd be ok. 295 is kinda a small tire for a truck, but again if lowered will help clearing.
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2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 6” lift 1999 GMC Yukon 350/4L60 4" SAS |
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#5 |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
I have CPP tubular control arms on the front, I'm not sure if that changes much with the ball joint issue.
I've got 2.5" drop spindles on the front and I will have Belltech 1" drop coils. On the rear I'm going to upgrade to heavy half 1950 lb (4+1) leaf springs that are flipped. Right now my truck sits a little lower than I'd like so I'm going to try to lift it just a bit, I think the new leaf's/coils will get me right where I want it but I can't tell you what it'll do until it's been done. I will attach an image in a minute that will show my trucks current/previous height prior to taking it apart. The tires I'm wanting to mount are 295/50/15's on the rear and (I think) 255/60/15's on the front. ![]() ![]()
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD Last edited by HunterRotten; 01-04-2017 at 07:03 PM. |
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#6 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,455
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Re: Got Cragars, will this backspacing work or do I need to exchange?
As low as that is I don't think there gonna fit.....
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2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 6” lift 1999 GMC Yukon 350/4L60 4" SAS |
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#7 |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
I'm going to go from a near 5" drop (I think..) to 3.5" on the front and I'm hoping to gain an inch or two on the rear or more. I used a mcgaughy's kit that dropped me a lot more than I expected..
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD |
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#8 |
67-72 parts collector,…
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Location: Mid-MO
Posts: 22,698
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Re: Got Cragars, will this backspacing work or do I need to exchange?
What's the specs on the wheels that are on it now?
That should tell you if the new wheels will work or not.
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Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823 |
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#9 | |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Quote:
15"x8.5" wheels 3.25" backspacing (only measured rear) 225 70 15's in the rear 215 70 15's in the front
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD |
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#10 |
Registered User
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,227
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Re: Got Cragars, will this backspacing work or do I need to exchange?
The fronts will likely fit, and may need trimming of the control arm as stated above. Only grind off what you need to clear the wheel and the wheel weights.
The rears will not fit - the tires are going to rub on the back fender, or hit the fender on every bump if they aren't touching from the get-go. You really want 5" backspacing for a 10" wheel at the back if you stay at the height you are now. You could raise it up a couple inches, but I really like the look it is now. It will be awesomer with those wheels. And awesomerestest if you can actually drive it with Cragars (5" backspacing).
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1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, boosted-LS 1977 Silverado: Shortboxed & dropped, potato-potato V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag Lotus Super 7 Replica: Scratch-built street-legal rollerskate |
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#11 |
Diggin The SquareLife
Join Date: Dec 2010
Location: garland,tx
Posts: 1,933
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Not gonna fit
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#12 |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Will it not fit no matter what? Or if I lift it a few inches will it fit?
I plan on raising both sides of the truck at least 1.5" if not more, I won't know until I test out the 1950 lb (4+1) leaf springs on the rear with the flip kit. I cannot drive the truck at it's current height, exhaust pipe and control arms do not clear my driveway. Also running a set of caltracs in the rear, something else to worry about with clearance however there is a lot of space on the other side of the wheel so I don't think that will be a problem.
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD Last edited by HunterRotten; 01-04-2017 at 09:44 PM. |
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#13 |
Registered User
Join Date: Jul 2016
Location: Qld Australia
Posts: 70
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Re: Got Cragars, will this backspacing work or do I need to exchange?
If got the rims already......jack it up and try em out.....only real way your gunna see fitment at your current ride height/caltracs
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#14 |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
That has been done already, atleast on the rear set. My truck is just a stripped bed on a frame right now so it's hard to tell.. I also don't have it sitting where I want it yet.
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD |
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#15 |
Registered User
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,227
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Based on the pictures, the rear tires tuck inside the rear fender - their tops are higher than the fender edge.
The tire sidewall will bugle slightly wider than the rim itself. This means the sidewall will protrude outside your fender, and the tread will still hit the fender edge. A 295/50R15 is slightly shorter than a stock tires, but you're really going to want to have a minimum of 2" travel (I'm guessing) before the tire hits the rim, or ridiculously stiff springs to stop it from moving at all. You might be able to roll the fender edge up and slightly -flare- the box side to clear, but it's going to take work. (I did this with my last truck, a Nissan Hardbody with Toyota Tundra steelies - the sidewalls were getting cut by the fender edge).
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1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, boosted-LS 1977 Silverado: Shortboxed & dropped, potato-potato V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag Lotus Super 7 Replica: Scratch-built street-legal rollerskate |
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#16 | |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Quote:
I am hoping to gain an inch or two in the rear with the new (1950 lb) 3/4 ton springs. I have a very worn out and saggy leafs in the pictures provided that are rated for 1250 lbs. The truck is already very stiff with a super thick CPP sway bar front and back. Polyurethane bushings, caltracs, and then even soon to have the thicker 3/4 ton springs. So the question is, how much of a drop from standard 1/2 ton GM square body can you do before this size backspacing becomes a problem. I think if this answer could be provided it would answer all my questions. Right now I'm at a crazy 5"/7" drop and I want to be at about 3.5"/4.5" from stock height.
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD Last edited by HunterRotten; 01-05-2017 at 12:36 PM. |
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#17 |
Registered User
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,227
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Whatever height has the fender edge a minimum 2" above the tire. 3" would be better.
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1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, boosted-LS 1977 Silverado: Shortboxed & dropped, potato-potato V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag Lotus Super 7 Replica: Scratch-built street-legal rollerskate |
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#18 |
Diggin The SquareLife
Join Date: Dec 2010
Location: garland,tx
Posts: 1,933
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Re: Got Cragars, will this backspacing work or do I need to exchange?
I had 15x10s wth 275/60/15 an 6" drop.....an my fit with no issues i also had 5" backspacing on the wheel
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#19 |
Registered User
Join Date: Sep 2007
Location: Wichita Falls, Texas
Posts: 459
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Re: Got Cragars, will this backspacing work or do I need to exchange?
CB may stand for center bore. The diameter of the part of the rotor or axle that sticks out past the flange. Thats all I got......
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#20 |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
We are going to jack the front end up and test out the 15x8's on the front with the 4.25" backspacing. If they don't fit then it's all going to be returned. If they do fit then I will then test the same 15x8's on the rear and see clearance there. If they fit on front and back then this will most likely be the course of action (running 15x8's all around) but if I gain enough clearance to not worry about digging into the sidewall on a 15x10 then I will keep what I have.
Sometime in the next 48 hours we will know about the 15x8 fitment, I'll update about it here as I can't be the first person trying to run cragars.. While we are on the topic of wheels and tire fitment, what is the preferred tire here? I know the selection of tire for such a wide 15" tire is slim pickings but there are some options. I've decided to go with the Mickey Thompson sportsman S/T's all the way around.
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD |
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#21 |
Registered User
Join Date: Sep 2015
Location: the colony
Posts: 102
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Re: Got Cragars, will this backspacing work or do I need to exchange?
1/4 inch may not be a deal breaker on the front. I am running 15x8 with a 4" BS and a 245/60-15 on the front of mine with a 5" drop. I get the normal control arm rub at full lock and have to use tape on wheel weights. I am running a 15x10 with a 5.5" BS on the rear. Most run a 5" BS but mine likes the 5.5 for some reason. The rear being a 15x10 with a 4.25 BS is going to hang out of the fender well more. I am at 7" drop in the rear and a 295/50-15 is right at or a little more up in the arch so unless you raise it up I don't think 10's will work. I am pretty sure the 8's will work on the rear, at least that's what I think you are going to try?
I have a set of Cragar SS's in the garage waiting for the sun to come out so I can put them on. 15x8 and a 15x10. The 10's are custom built to my specs from Newstalgia wheels. Alex there is a good guy to deal with if you want to spec some for your truck. |
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#22 |
Diggin The SquareLife
Join Date: Dec 2010
Location: garland,tx
Posts: 1,933
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Re: Got Cragars, will this backspacing work or do I need to exchange?
I had 275/60/15 on my 15x10
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#23 |
Registered User
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,227
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Re: Got Cragars, will this backspacing work or do I need to exchange?
I run 275/60R15's on my 15x10's. They look just like the ones above, a tick too narrow for the rim, but it's fine. When they are finished, I will be buying 295/50R15's.
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1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, boosted-LS 1977 Silverado: Shortboxed & dropped, potato-potato V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag Lotus Super 7 Replica: Scratch-built street-legal rollerskate |
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#24 |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Going to do more measurement tonight, it's been a busy weekend. I'm just as confused as I was before but my bed and axle aren't square. I think now the rears will work fine once I get my small lift.. but the front has clearance issues and will need a spacer. It's all up in the air for now until my dad and I get back in the garage.
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD |
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#25 |
Registered User
Join Date: Oct 2016
Location: Kentucky
Posts: 385
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Re: Got Cragars, will this backspacing work or do I need to exchange?
Sorry if the site flips the photos.
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1978 Hawaiian Blue GMC 454/Tremec TKO 500 BUILD THREAD |
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15x10, 15x8, cragar, tires, wheels |
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