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Old 01-04-2017, 06:36 PM   #1
HunterRotten
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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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Last edited by HunterRotten; 01-04-2017 at 06:51 PM. Reason: added tire info
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Old 01-04-2017, 06:40 PM   #2
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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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Old 01-04-2017, 06:43 PM   #3
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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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Old 01-04-2017, 06:54 PM   #4
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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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Old 01-04-2017, 06:56 PM   #5
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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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Old 01-04-2017, 07:06 PM   #6
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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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Old 01-04-2017, 07:09 PM   #7
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Re: Got Cragars, will this backspacing work or do I need to exchange?

Quote:
Originally Posted by b454rat View Post
As low as that is I don't think there gonna fit.....
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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Old 01-04-2017, 07:57 PM   #8
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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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Old 01-04-2017, 08:29 PM   #9
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Re: Got Cragars, will this backspacing work or do I need to exchange?

Quote:
Originally Posted by lolife99 View Post
What's the specs on the wheels that are on it now?
That should tell you if the new wheels will work or not.
They are Weld's Aluminum wheels. I don't know a P/N or much info besides a quick trip down to the garage. I only measured the rear but I'm certain they are all four the same.

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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Old 01-04-2017, 09:17 PM   #10
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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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Old 01-04-2017, 09:20 PM   #11
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Re: Got Cragars, will this backspacing work or do I need to exchange?

Not gonna fit
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Old 01-04-2017, 09:32 PM   #12
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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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Old 01-05-2017, 12:56 AM   #13
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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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Old 01-05-2017, 07:53 AM   #14
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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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Old 01-05-2017, 12:03 PM   #15
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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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Old 01-05-2017, 12:30 PM   #16
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Re: Got Cragars, will this backspacing work or do I need to exchange?

Quote:
Originally Posted by SkinnyG View Post
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).
Thank you for the reply, the pictures are confusing me with peoples answers as the truck sat too low and I plan on lifting it. These wheels will not be on the truck at its current height. do not think under any circumstance these wheels will work at the current height of the truck. I do not like how low it is and do not want any wheel or tire tuck.

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.

Last edited by HunterRotten; 01-05-2017 at 12:36 PM.
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Old 01-05-2017, 09:42 PM   #17
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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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Old 01-05-2017, 09:48 PM   #18
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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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Old 01-05-2017, 09:50 PM   #19
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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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Old 01-06-2017, 06:00 PM   #20
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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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Old 01-06-2017, 09:02 PM   #21
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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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Old 01-06-2017, 09:23 PM   #22
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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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Old 01-06-2017, 09:54 PM   #23
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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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Old 01-08-2017, 06:06 PM   #24
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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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Old 01-08-2017, 06:20 PM   #25
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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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