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Discussion Starter #1
Hey guys, I've been looking at buying a set of CCW wheels for the street, and just using my stock wheels to mount autocross tires on.

I am curious to see what the biggest tire and wheels size that will fit on the car? I believe I'll go for the polished 3-piece wheels, but will I be able to fit the 18's underneath the car?
 

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The salesman I bought my GTO from has an '04 GTO with 18s on it. If I recall his tire size is 245/40/18.
It is nice to see someone else autocrossing their GTO. It is a good car for this in its SCCA class.
 

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Discussion Starter #3
Great, 18's will work with me. I'm not looking for something huge, I just want some nice looking wheels for the car.

Yes, it should be a good car for autocross, can't wait for the 31st which will be the first time I'll get to autocross this car. It's going to get some taking used to... right now I'm autocrossing a C5 corvette on race tires, so it will take some time!
 

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I have a set of 19" ROH wheels from Oz on mine. With a 245/35/19 tyre on them, they are .5" taller than the stockers. The front wheels just touch the inner fender well and could not go any larger because of the coil over shock in the fronts. In back you can get up to a 275 on the rear without having to roll the fender lip, if you buy Nittos.
 

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My 18's rubbed with 285's because of the offset (in the rear) and started shredding the tire. I had to switch to 245 Dunlop's (no charge through Discount Direct AKA America's Tires and I got to keep my 18's. I love them. I was suprised to here that the tires were rubbing in the *rear* of a RWD car but it's true. I think 20's may be an issue on this car unless you roll the fender. I think 18 looks perfect. After it quits raining I will get some pics up!
 

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Discussion Starter #8
Yeah, I'd love to see some pics.

I was afraid of the rubbing issue. The car looks great soo low to the ground, with little clearance in the fenderwells, but supporting larger wheels will be an issue.
 

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Discussion Starter #9
What is the offset and backspacing on the 18" wheels that two of you have mentioned before? I found a set that is off of a Porsche 911, I'm just curious if these will fit on the Goat. Hehe, the wheels are 9" wide in the rear, and I believe 7" wide in the front with a front offset of 80mm, and the rear offset of 85mm.

Anyone know if this will fit?
 

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I doubt if that offset from the Porsche will work on the GTO. The offset is what people are having so much trouble with. Here is a chart that shows you where you need to be.
 

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OK, that didn't work very well. It says the file exceeded my limit so it wouldn't upload. Here's the info:

Width.......................Offset.....................Width of Tire
7.0______________+26/+65_________215/225/235
7.5______________+33/+61_________215/225/235/245
8.0______________+39/+55_________225/235/245
8.5______________+45/+48_________235/245/255
9.0__MAX________+48_____________245/255

Rear Only
8.0______________+36/+65_________245/255
8.5______________+42/+65_________245/255
9.0______________+48/+65_________255/265/275
9.5______________+55/+64_________265/275/285

Offsets greater than shown above will rub on rear fender lip. (25MM fender lip)

I think this info came from BigWheels.com but wouldn't swear to it.
 

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Discussion Starter #12
Hey Glenn, thanks for the info, I really appreciate it.

I hope to have wheels on the car for spring, no rush now after next weekend it will be in storage until the weather starts getting nice again. But I just can't get over how nice the CCW 3-piece wheels look on the C5's, and I would imagine they would look great on the GTO as well. Hopefully I'll be one of the first!
 

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GlennH said:
OK, that didn't work very well. It says the file exceeded my limit so it wouldn't upload. Here's the info:

Width.......................Offset.....................Width of Tire
7.0______________+26/+65_________215/225/235
7.5______________+33/+61_________215/225/235/245
8.0______________+39/+55_________225/235/245
8.5______________+45/+48_________235/245/255
9.0__MAX________+48_____________245/255

Rear Only
8.0______________+36/+65_________245/255
8.5______________+42/+65_________245/255
9.0______________+48/+65_________255/265/275
9.5______________+55/+64_________265/275/285

Offsets greater than shown above will rub on rear fender lip. (25MM fender lip)

I think this info came from BigWheels.com but wouldn't swear to it.

Good info, but I am not sure I understand it. Which offset is correct? Is this saying you can get 9.5" wide rear wheel with a 285 series tire and +55 offset, or the same with a +64 offset. That's almost a 1/2 inch difference... I must be missing something.
 

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There's a guy over at ls1gto.com that fit 315's in the rear...they were pulled of a WS6...he said they fit ok but were pretty tight...sounded like a decent setup for the track but not for every day.

If you roll the fender, you'll definitely be able fit a larger wheel/tire
 

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I build semi trailers and i noticed some wheels and tires the other day that would be some hella drag meat.....465/60/22.5 , instead of the trailer having duals with each tire, it just had one huge on, i'd imagine with all 4 of those tires, it would be hard to turn the trailers, but on the other hand, it would be different to see a gto tubbed out to fit those bad boyz
 

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BigJim said:
are there any plans to make the tires bigger than 225s on the 2005 models? maybe 245s?
On the GTO? The 2004 GTO did have 245 tires.
 

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my bad

lol guess that what i get for not doing my research for some reason i thought the 2004s had 225s. you would think gm would make them as big as they could go?
 

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Lots of factors to consider because not all drivers drive their cars hard. 245 tires will be quiet, get decent traction, better for mileage, look fairly beefy.. It's a good size I think that fits a broad market of users I think. People who need wider tires can upgrade in the aftermarket because those kinds of people munch their tires up no matter what size they are. Pretty much any car sold today has room to put bigger tires on it.
 
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GMpartsdirect.com has two different sets of 18" wheels with tires and all for about $2200. Go to their website and look for the Aftermarket link, then for the MC2 link, then select Pontiac, then select GTO and you will see two different set of original '04 GTO original optional 18" wheels with tires tha t in my opinion look real good. They are not generic aftermarket wheels that you will find on every ricer around, but 18" wheels specific for the GTO with its Pontiac Logo and all.
 
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