Rotary Nut

What is the diameter of the center hub (used for hubcentricity)?

syntrix

I just measured one of my stock rims in the garage.

Took a business card, lined up and marked. Then put it against a meter stick.

Looks like the widest is 70mm, and it does taper inward. I'd be worried about the taper if you are looking at aftermarket rims

Once again, this is NOT a scientific measurement

Rotary Nut

Thanks syntrix!

Ned M

iTrader: (2)

I think you'll find that most aftermarket rims are cut to 72 or 73mm so they can fit as many hubs as possible using centering rings.

syntrix

But the question/topic is about being hubcentric.

NP RN!

Ned M

iTrader: (2)

Then why did you post a non-scientific measurement? If Rotary Nut's ordering custom rims, the mfr will know what the hub size is and make them hubcentric. If he's getting mass produced aftermarkets, a reputable dealer will provide centering rings.

syntrix

Why troll all day long?

If he needs rims that fit hubcentrically, they will have to be tested. At least this is a baseline for him to work off of. Not all tapers are the same, and having a rim that is truly hubcentric can eliminate a lot of problems in the future.

I believe centering rings are out as the thread first mentions being hubcentric.

Let me quote the first post in this thread for clarity:

Keep it on topic. Simple as that!

Ned M

iTrader: (2)

I was trying to be helpful. Didn't realize only moderators could do so. TTFN

oosik

ok, you win! what's hubcentricity?

(i'm searching in the meantime)

oosik

nvm, found a defintion:

for those that give a rodent's brown-starfish:

"The centerbore of a wheel is the size of the machined hole on the back of the wheel that centers the wheel properly on the hub of the car. This hole is machined to exactly match the hub so the wheels are precisely positioned, minimizing the chance of a vibration. With a hubcentric wheel, the lug hardware will not be supporting the weight of the vehicle, all they really do is press the wheel against the hub of the car. Some wheels use high quality, forged centering rings that lock into place in the back of the wheel. This is an acceptable alternative."

Rotary Nut

Thanks to all who responded. It was starting to get a bit amusing there for a while! But you all got your point across. 70 mm center bore it is!

maxcooper

For reference, the FD (93-95 RX-7 in U.S.) had 67.1mm hubs (i.e. wheels with a 67.1mm centerbore would be hub-centric on the FD).

I don't know if the RX-8 is the same, but I think that some hub-centric wheels from an FD have been mounted on an RX-8 sucessfully, so it stands to reason that the RX-8 has the same sized hub centers or smaller.

-Max

syntrix

That could be very true.

I'm measuring at the back of the rim, ie the widest part at 70mm.

Then it tapers in... that's the smallest part, which may be very well how the hub is measured!