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Old 02-24-2013, 06:06 AM   #1
brando1118
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offset and backspace rear fender clearance question for 19x9 wheels

Hello all,
As the title of the thread states I'm looking for info from anyone that is running 19's on their C3 or are much more knowledgeable about wheel fitment on our C3's than I am. So here goes:
The wheel:
Concept 1 CSL 5.5. BMW bolt pattern 5x120mm
They do not make custom sizes. What they offer is what you get.

wheel measurements: 19x9 with 15mm +offset.

With no wheel adapters and current +15mm offset the backspace of this wheel is ~5.6 inches.
I've never shopped or used spacers, but I'm assuming (dangerous) that they make 15mm spacers to bring my backspacing into a safer 5 inch range.

Now we get to my question: I LOVE wheels with a deeper dish. The choices of offsets from Concept 1 are +15mm (deeper dish) or +35mm (not as deep). Will the lower offset 15mm number plus 15mm adapter/spacer push my wheel outside of my stock fenders? I'm referring to the rear wheels here. Looking to run a 275/35 or 40 series tire. Whichever one is closest to stock wheel diameter.
Thanks!!
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Old 02-25-2013, 01:28 PM   #2
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There are enough differences in body and fit tolerances that you really aren't going to know unless you measure.

Try this...

http://www.billetspecialties.com/ass...Guide-2013.pdf

This guide should allow you to determine the needed spacings.

On a side note you might want to check that bolt pattern. I know it's close but if I remember correctly 5x4-3/4 = 5x120.7mm. Some will say it's close enough...... IMHO any sideways pressure on the wheel studs will weaken (stretch) them at the base. Not a good thing for a wheel stud.
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Old 02-25-2013, 05:17 PM   #3
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Thanks 7TRoadster,
Yes, the more I learn about the ability of adapters to make things match up perfectly, you can bet I will go from the 5x120.65mm on the hub to the 5x120mm on the wheel. I've decided I will purchase one rim and have one tire mounted. I will make adapters out of wood and do the trial fit.
Thanks for the reply and the helpful advice.
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Old 02-26-2013, 12:49 PM   #4
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I can't add anything to the conversation regarding if the tires will stick out or not, but I can add that the BMW wheels, lug pattern wise, will absolutly fit...I had them on my '72 before I changed to a 20" wheel with the Chevy bold pattern. I also used them on a '64 Impala build. I can also add that I'm running 1" adapters on all four wheels and have been for 8+ months and for at least 5000+ miles with no issues whatsoever. Just my 2 cents.
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Old 02-26-2013, 03:55 PM   #5
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Clemsontiger,

I don't mean to start a thread war here but isn't this a photo of your car after running the BMW wheels?


http://www.digitalcorvettes.com/foru...157976&page=11


See post # 157
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Old 02-26-2013, 05:22 PM   #6
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All,
After doing some research on the plethora of different options for adapters, I'm going to purchase a set of adapters that bolt to the hub of 5x120.65mm and then will convert to 5x120mm, plus be hub centric to the hub and to the center of the wheel.

http://www.motorsport-tech.com/
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Old 02-27-2013, 02:18 PM   #7
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Haha, yes...but the fact that I was running BMW wheels and/or adapters wasn't the issue...the issue was not getting the adapters tight (not my doing). The point I was trying to make was, you CAN run the BMW wheels, no problem...you CAN run the adapters, no problem...assuming you get them tight when you put the on. I've run my current wheels and adapters 5000+ miles with zero issues.

If you have the choice, like OP does, go with the adapter that will convert BMW to Chevy...but you don't have to.

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Originally Posted by 7TRoadster View Post
Clemsontiger,

I don't mean to start a thread war here but isn't this a photo of your car after running the BMW wheels?


http://www.digitalcorvettes.com/foru...157976&page=11


See post # 157
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Old 02-27-2013, 03:03 PM   #8
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Quote:
Originally Posted by clemsontiger View Post
Haha, yes...but the fact that I was running BMW wheels and/or adapters wasn't the issue...the issue was not getting the adapters tight (not my doing). The point I was trying to make was, you CAN run the BMW wheels, no problem...you CAN run the adapters, no problem...assuming you get them tight when you put the on. I've run my current wheels and adapters 5000+ miles with zero issues.

If you have the choice, like OP does, go with the adapter that will convert BMW to Chevy...but you don't have to.
Running the wrong bolt pattern can easily damage the wheel studs. I'd never run BMW wheels on a GM hub. You'r advice above could cause major damage and injury to a fellow enthusiast.
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I'm taking care of my procrastination issues, just you wait and see.
Old 02-28-2013, 05:18 AM   #9
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Quote:
Originally Posted by blckslvr79 View Post
Running the wrong bolt pattern can easily damage the wheel studs. I'd never run BMW wheels on a GM hub. You'r advice above could cause major damage and injury to a fellow enthusiast.
With your concern taken into consideration-were are talking about .65 of a millimeter here.
Would it be better to get the proper adapter? sure I guess but is it neccessary? IDK
On the other hand-5000 miles on the BMW wheels isn't exactly a tell all test IMO. Tell me 50,000 miles and then.......
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Old 02-28-2013, 07:05 AM   #10
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My advice is to run whatever you want to run. I'm not forcing anybody to run anything. The fact is, people run BMW wheels on Chevy lug patterns all the time because there are a lot more wheel options in the 19-24" or larger wheels in the 5x120 pattern. You'll see this a lot more on "big wheel" cars than you do on hot rods, but it's out there. I'm not trying to tell you that it's a "perfect fit, run with it"...I'm just saying, if that's what you want to do, it can and has been done. I'm not sure that changing anything, including something as simple as going to a 17 or 18" wheel won't cause some issues over 50k miles. These cars were designed and engineered to run a specific size wheel and tire and any change to that will affect the way bearings, seals, brakes, etc wear.

Quote:
Originally Posted by blckslvr79 View Post
Running the wrong bolt pattern can easily damage the wheel studs. I'd never run BMW wheels on a GM hub. You'r advice above could cause major damage and injury to a fellow enthusiast.
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