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Discussion Starter · #1 ·
My GT came with these on them....they appear to fit well and clear everything with room to spare..it has 195/50/16 tires.... I do think it raised the car some...all cars sag as the springs loose strength so not sure how much to compare from stock....or even where to measure... Looks fine and seems to fit....I did have a problem with the lugs coming loose...I doubt they were ever torqued.....also the Opel lugs have a short taper...I ordered a new set of lugs with a long 60 degree taper for aftermarket wheels...I think the torque thing loosened the lugs.
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Discussion Starter · #2 ·
Notice the hub center caps...they are Opel ...I found them on German EBAY....the Cobalt center caps are the exact same...both stick on caps...just a few bucks...
 

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They look good on your car.

If the hub size is larger than the Opel hub size, then you need some hubcentric rings. If that is the case, THAT is likely why the lugs came loose.
While it wouldn't hurt to find and install hub-centric rings, the factory Opel rims and virtually all the aftermarket rims fitted to this era of Opels are actually lug-centric.
 
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I would like to see the factory documents that show the factory Opel rims are not hubcentric. Until I see that, I will agree to disagree with you.
Hubcebtric rims weren’t really a ‘thing’ when these cars were built.

Some Opel rims do contact the center register, though that area of the rim is stamped rather than machined. But, for example, the 4-spoke rims used on 1973 GT’s and various other models of Opels don’t come anywhere close to touching the center hub area. They are 100% located by the lug nuts.
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Discussion Starter · #7 ·
The fronts had 3/8" spacers on them....I would think the wheel would be hard to balance ....the spacer moves up and down when the wheel is loose... Yes they are indeed hub centric...but have tapered lug mounting... I bought some deep tapered lug nuts to center the wheels...I think that should work fine...the Opel nuts have a short taper....
I had not thought of boring the center of the wheel to the hub to match the axle...that would eliminate the use of the spacer..... easier yet is to machine my own spacers that are the exact 4X100.... The tires are 195/50/16 and appear to have plenty of clearance
 

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I would like to see the factory documents that show the factory Opel rims are not hubcentric. Until I see that, I will agree to disagree with you.
Hubcentric rims weren’t really a ‘thing’ when these cars were built.

Some Opel rims do contact the center register, though that area of the rim is stamped rather than machined. But, for example, the 4-spoke rims used on 1973 GT’s and various other models of Opels don’t come anywhere close to touching the center hub area. They are 100% located by the lug nuts.
Lynn, in the absence of finding "Factory" documents indicating that OEM wheels on these old Opels were lug-centric vs hub-centric, which I am pretty sure I have read but cannot easily reproduce, is RallyBob's assurance a sufficient substitute?

Just kinda' having some fun with you. Although I am a bit hurt that my assurance didn't provide the confidence you required. 😉
 

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I would argue that stamped wheels are likely not going to be hub-centric, especially from the 60's and 70's. For rims to actually be hub-centric requires tight tolerances and rims that were stamped and then welded together are going to have a somewhat rough tolerance compared to a forged or billet rim. For mass production where economy or cheap is the first priority, lug-centric is more inline with that.
 

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Early cars DID have hub centric wheels. I won't attest to Opel GTs but my 70 Ford LTD, 72 Ford Ranchero and 73 Dodge van all had hub centric.
 
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