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GTA Wheels Center bore

LeedomtoFreedom

New member
Joined
Oct 11, 2017
Location
Ingleside
GTA wheels have a 70.3mm center bore while volvo's are 65.1mm

Hubcentric adapters with a center bore of 70.3 would satisfy the GTA wheels but would be too large for volvos hub, meaning it would be suspended and only held in place by the studs, not resting on the hub?

Am I getting something fundamentally wrong here.
 
You don't need the center bore to match (so long as the wheel is larger than the hub). The lugs do the actual centering, and the center bore is merely a convenience for installing the wheels. You have to be considerably more careful when installing the wheel and torqueing the lug nuts, but it's not too bad. You have to be careful when tightining the first two lugs, as the conical nut will suck the wheel in to position, but it's certainly doable.
 
The lugs do the actual centering, and the center bore is merely a convenience for installing the wheels.
I always thought that the center bore was a better method for centering the wheel because they are machined to better tolerances? Made sense to me.
 
I was always taught that the center bore was what the wheel was resting on, and that most of the weight was held by the hub, not the studs.

Anyway what's the proper solution... I'm guessing custom wheel spacers but any other opinions are welcome
 
They are called Hubcentric spacers. You can get them custom cut aluminum or hardened plastic. I have used both and the good quality plastic are fine for about $20. Custom AL are about $100.

But yes, it is most advisable to run hubcentric spacers.
 
I was always taught that the center bore was what the wheel was resting on, and that most of the weight was held by the hub, not the studs.

Think about it this way: if the hub was supporting the load of the car, the fit would have to be so tight you'd need a hydraulic press to install the wheels. Nothing with the super loose slip fit like a hub center bore can really support any load, especially not in a dynamic way like on a spinning wheel.
 
Wheel adapters with the correct centerbore to match the hub and the correct diameter lip to center the wheel are superior to use because the stack (wheel + adapter) will be centered every time.

If the adapter centerbore is 70.3mm, then it will be located on the hub by the lugnuts. You might get it centered on the hub...but you might not.

When I've used adapters like this, it's not uncommon to have a vibration at a certain speed...maybe it shakes at 64mph, but it's smooth at 61mph and 66mph. It's annoying.

If you can find hub rings to make up the difference, that works.

I've used adapters from here:
http://wheeladapter.com/
http://www.motorsport-tech.com/

The first one used m12x1.5 studs. I didn't think the studs were very good quality. I chewed up a few and broke off a couple. On the plus side, the aluminum held up fine, and I just had to knock out the broken stud and pull in a new one.

2nd one, I specifically requested 1/2x20tpi studs. I also had them make the adapter with a longer lip to be sure it was deep enough into the wheel. My GM wheels had a wide chamfer on the centerbore.


Once the lugnuts are torqued, the clamping force holds the wheel against the adapter/hub. The studs are not seeing bending loads because you're not overcoming the friction between the wheel and adapter/hub. The centerbore is not needed to support the wheel / weight of the car.

100% weight transfer on 295 width Hoosiers on adapters. These wheels are centered by the lugnuts....the centerbore of the wheel is huge. Just make sure you torque everything properly and it's safe.

152754784.jpg


We used adapters on our 24hr lemons car with Corvette C4 wheels and I've tracked my 240 with adapters a few times. Additional brake heat hasn't been an issue. We never used loctite like some people...just torque the lugnuts properly.
 
Ive ran wheels that were center with lug nuts. It works but you will have to go home after a shop does it and jack it up and break all lugs loose and tighten correctly. I know run wheels with hub centric spacers and that is the only way to go. They are cheap too.
 
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