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2005 STS
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3 Posts
Discussion Starter #1 (Edited)
Gentlemen (and Ladies):

I have a situation which has stumped me and I’m hoping someone might help clarify things. I have a 2005 Cadillac STS, V6, RWD, Base Model, which I purchased used. A previous owner had after-market alloy wheels and tires installed (255/45-R18) all around.

Yesterday, I hit a giant pothole (everything’s bigger in Texas) resulting in a bent and cracked wheel. Unfortunately there was no spare, when I purchased the car, so at the time, I went on an adventure to find one. I located a compact spare which came from a car basically identical to mine (don’t know all the RPO codes for either, but same Year, Engine, Trans, Drivetrain and Trim level).

As I understand them, the specs for the original OEM wheel/tire are:
Bolt Pattern: 5x115mm
Thread: M12x1.5
Center Bore: 70.3mm
Width: 7.5”
Diameter: 17”
Offset: Positive of 51mm

The spare had the same specs, except of course, that the diameter is only 16”. With the same general specs and appearing identical to every photo I’ve seen of an OEM spare, I thought this spare would work. In short, it doesn’t. Yes the bolts line up with the holes, the center bore and offset look right, but it just won’t go on, because it hits the brake caliper. There’s an overlap of about 3/8” making installation impossible.

So I’m stumped. I even tried it on another spot on the car, but same thing. There is nothing obviously wrong with either the operation of, or appearance of the hub, rotor, or caliper which might account for the conflict. Thinking I’d missed an item in the specs, I double checked everything I can about wheel fitment and find no reference to the Internal Diameter of a wheel. I’m guessing the anomaly is not with the spare, but rather with the caliper. I’ve done probably 50 brake jobs over the years, but fortunately never had to replace a caliper. Can you get different sized calipers for the same model car? Could it be oversized? Was that an option on these cars? Or is there something I’m missing?

Any thoughts or advice would be most appreciated, as I can’t drive it until the wheel is repaired (if possible) nor can I afford a whole new set of wheels and tires.

Thanks in advance for your help!!
 

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2006 STS V8 1SF RWD
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6,487 Posts
Pretty sure my OEM spare is a 17...A 16" wheel won't clear the brakes. There are 3 brake options for the STS; JL9 (base), JE5 (performance) and J56 (Heavy duty). The front JE5 (323mm) rotors are almost an inch larger in diameter than the JL9's (303mm). The J56 (Brembo) are even larger at 353mm.

Get a 17" spare and you'll be fine.
 

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2006 V6 STS RWD
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305 Posts
Can't say you're wrong, since I bought my '06 used and I've never had the spare unclamped from the trunk, BUT I just checked and my spare's a T125/70R16. Looks all brand OEM new and seems to be an exact fit for the jack stuff inside it. I've got the 235/50 & 255/45 17" build and the trunk sticker agrees. It would make sense to just use one spare for all builds, since the outer diameter is all that counts. Maybe there's some aftermarket caliper/rotor stuff on the OP's car?
 

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2006 STS4 V6
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436 Posts
Can't say you're wrong, since I bought my '06 used and I've never had the spare unclamped from the trunk, BUT I just checked and my spare's a T125/70R16. Looks all brand OEM new and seems to be an exact fit for the jack stuff inside it. I've got the 235/50 & 255/45 17" build and the trunk sticker agrees. It would make sense to just use one spare for all builds, since the outer diameter is all that counts. Maybe there's some aftermarket caliper/rotor stuff on the OP's car?
If the OP has JE5 a 16" spare will not clear the caliper. I know this first hand.
 

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2006 STS V8 1SF RWD
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6,487 Posts
If the OP has JE5 a 16" spare will not clear the caliper. I know this first hand.
I have JE5 brakes with factory 18's - I used 1st gen CTS 17's (same as STS 17's I believe) as winter wheels and they barely cleared the calipers, less than a half inch of clearance.
 

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2005 STS
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3 Posts
Discussion Starter #7
Thanks for all the input. I anticipated the advice to get a 17" spare and so I got one this evening. Promodmerc is correct that the clearance is tight but it fits and that's all that counts. Wouldn't it be great if there was a standard for all Cadillacs...hell I'd be happy if there was one just for each model. But no, the '05 STS even has a different bolt pattern, depending on the sub-model, 5x115 or if you have an STS-V you get another hole...6x115. GM's gonna have to wait, first on my list will be a battle with cell phone manufacturers, over charging cable incompatibility. Wishful thinking. Back to reality and an STS I can again drive. Love the forum and all the info...keep it up. Thanks again y'all!!
 
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