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Pontiac GTA Wheels

cordova240

New member
Joined
May 12, 2013
Location
New Mexico
I know a few of you guys are running GTAs on your 240s. Im interested in purchasing a set of 16x8s. What all do I need to make them work?:

What is the bore of the gta's 16x8, 70.1mm??
I need to know so I can order custom adapters from motorsport-tech.

How thick of adapter, 25mm?

What stud size?

Thanks!
 
70.3mm center bore and your car has a 65.1mm center bore.

M12x1.5 is what stud size is factory for the gta wheels.

I have a set of adaptec Motorsport-tech adapters for gta wheels that I couldn't use. 19mm thick if you're interested
 
Thanks for the quick reply, Would the 19mm be too thin for the original studs? thought it needed 25 to clear..?

It would. You'd have to trim the studs down some to get them to clear.

Sorry for slight thread jack here, What adapters are needed on a 74 144?

It would be hard to fit them unless you're okay with a lot of poke. Like a lot. Even if you pieced together a full set of the et16 wheels you'd still be at a minimum of et-3 after adapters and that'd be flush and probably require a 195 tire. The et0 pair would just be ridiculous.
 
mine are 1" (25.4mm) think all the way around.

although i wish i would have went a little wider in the back. maybe 1.25"

5fe4819b-314f-405a-9d50-6e5ac786364a.png

11707516_431430223708925_1037629244617583529_n.jpg
 
Ok so say I did grind the studs down a little to fit them would the 19mm pose a problem with the wheels hitting anything like struts, brakes etc..?

Nope you will be good to go if you cut them down but I'm not sure you can get a factory wheel back on safely after that. So you might need a 5x4.75 spare.
 
Take a look at what chris gilmour^^ had to do to his rear arches to clear 25mm adapters. Trimming the studs will be easier than what you'll have to do to get a decent sized tire on there with 25mm

Go with the 19mm and dont look back imo
 
Yea not sure I wanna deal with that

You might be able to get a steel wheel back on but I'm not really sure. That's how they were on this car:

http://forums.turbobricks.com/showpost.php?p=5119797&postcount=1

Take a look at what chris gilmour^^ had to do to his rear arches to clear 25mm adapters. Trimming the studs will be easier than what you'll have to do to get a decent sized tire on there with 25mm

Go with the 19mm and dont look back imo

Also this. I mean there's nothing wrong with the way he did it but I'd imagine it's more work. I doubt you'll get them to clear with just a standard rolled fender.
 
It had 19mm front and 20mm rear. Or maybe the other way around.

What does the back pad of a GTA wheel look like? On my 142 I milled some pockets in the back of the wheels so the studs would have somewhere to go.
 
I havnt gottin ahold of any gta's yet, so not sure..I think trimming the studs will be the way to go and just have a 5x120 spare.
Pming you fortbrick
 
Mine had ~3mm pockets from the factory. Go over 20 and you will have to do irreversable/possibly damaging work to your rear arches. Even @19mm there needs to be massaging depending on how low your car is and tire size.

On the other hand, you could spend an hour and trim your studs. If you want to go back just pop in some new ones for under $40
 
Alright, I'll try to summarize here.

Yes, you have to trim the studs. There are no relief cuts in the gta wheels for bolt on spacers or adapters to clear. You will need 40 new lug nuts for the car; 20 short lugs that fit inside of the adapters between the adapter and the inside of the wheel, and then the normal 20 to attach the wheels to the adapters. Using proper torque settings is important as always and there are plenty of threads left on the studs after trimming. As said earlier if you want to go back to stock wheels, you'll need adapter style spacers or to change out the cut studs for stock ones.
 
Wait so if I trim the studs will there still be enough threads to torque the adapters down?

Yeah it'll still work. Bolt the adapter on and mark each stud where it's flush with the lug nut and cut it there. You'll still have full thread engagement.

I know someone else who used 25mm adapters on an '88 and actually still had to cut the studs just a little bit to get them to clear.
 
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