Learn me: Hub centric rims

I picked up some used rims for my 06 mustang from a fellow autocrosser.  He had me pick up some hub centric rims, which I don't believe I had ever heard of, or used.    I had an issue with them before I used them first time, so I did not.  I am now reading that they are necessary and they are not.  The guy who sold me the rims is an engineer (and a far better driver than I).  What does the hive say?

Thanks!

Are we talking hubcentric rings?  If yes $10 to $15 will get you metal or plastic of your needed size.  Too cheap not to use.  

Your cars factory wheels have a center bore size that is correct for your car.  The wheels actually fit to the car riding on the lip of the center hub and then the lug nuts keep the wheel tight to that lip of the center hub.  

If you then buy aftermarket wheels or wheels not properly fit to your car the center hole of the wheel may be too big for the lip of the hub.  These rings then fill in that gap so the wheels with the big center hole can rest correctly on the smaller center hole of your car.  

It is somewhat akin to...if you can throw the hotdog down the hallway this will tighten everything up and make it work better.  

Sample video quickly found...

An even better video...

In reply to thedoc :

Your car is a '06 Mustang. 

What are these new wheels from?  

What brand/make are the new wheels?

Some centering ring talk in our M3 project series, too, and thank you, John, for sharing that video that we made on this very subject. 

I would avoid the plastic ones unless you're just on the street. I've melted them before from brake heat (probably not a risk on the street) and when I replaced them with aluminum rings, my routine lug-nut-loosening problem on tracks with aggressive curbing/aggressive use of curbing completely went away.

As noted in the vid, hubcentric wheels (or hubcentric rings) are for helping you to locate the wheel on the hub when installing, assuming you have modern wheels with tapered or conical lug nuts. Once you have the lug nuts properly centered and torqued, THEY are holding the weight of the vehicle, not the hub itself. 

short answer: it's perfectly fine to run a larger hub bore on your wheel PROVIDED you properly torque everything down in a star sequence so the lug tapers center the wheel.  We've run many enduro races without hubcentric wheels, just have to make sure they're torqued correctly.

There are billions of wheels on the road right now that aren't hubcentric.

Here is the key.  Wheels absolutely must have a means of properly centering themselves on the hub.  The majority of wheel lug nut styles are a tapered or acorn seat, so if that's the case, that is what centers the wheel.  As you tighten the lug nuts, the conical seat forces the wheel to be centered on the studs.  No hub-centric rings required.

If you have mag-style lugs, you must have hub-centric wheels or rings because they don't have a tapered seat.

But if you look at aftermarket wheels, they often make the hub bore larger than the biggest hub they might fit.  6x5.5 wheels are used all over the place; Ford, Jag, GM, Toyota, Kia, Hyundai, Honda, Lexus, Mazda, Mitsubishi, Jeep, Nissan.  All of them have different hub bores, so aftermarket wheel manufacturers make generic offsets in that bolt pattern to fit all of them.  The way they make it work is by making hub bores big enough to fit the biggest one and then making the holes in the wheel require tapered lug nuts so they stay centered.

In reply to John Welsh :

John, thanks for all the information.  The new wheels are Enkei.

irish44j (Forum Supporter) said:

As noted in the vid, hubcentric wheels (or hubcentric rings) are for helping you to locate the wheel on the hub when installing, assuming you have modern wheels with tapered or conical lug nuts. Once you have the lug nuts properly centered and torqued, THEY are holding the weight of the vehicle, not the hub itself. 

short answer: it's perfectly fine to run a larger hub bore on your wheel PROVIDED you properly torque everything down in a star sequence so the lug tapers center the wheel.  We've run many enduro races without hubcentric wheels, just have to make sure they're torqued correctly.

For sure I have them torqued, I missed one wheel once and will not make that mistake again

 

In reply to irish44j (Forum Supporter) :

And don't zing the first lugnut to max torque before seating all the others...

I've seen lots of lug bolts shear off. I've never seen an axle hub shear off.

I realize the intent of hub centric is for centering, but I sure like my wheels fitting snug to the axle hub in addition to the lug bolts. I think the odds of shearing a lug bolt are significantly reduced when there is no movement against the studs because the center of the wheel is held firmly in place by the axle hub.

If you have tapered lug nuts, your wheels are lugcentric.  The pilot is mainly there to help you get started, but it is completely unneccessary.

Well, it's REALLY helpful on cars with lug bolts, but once the wheel is on it does nothing.

I don't bother with the rings. Seat thewheel in the air with the lugs, snugged well, then torque on the ground. I've run 120+ on wheels installed like that on track and no issues to date

In reply to SVreX (Forum Supporter) :

I've had a drive flange shear off and the wheel went with it. Does that count?

We sell hub centric rings because people get wound up without them because the Mazda gods bestowed hub centric stock wheels on the Miata. But it's just for convenience.

In reply to Keith Tanner :

All the Korean cars are hub centric OE wheels as well but we have the odd 67.1mm hub bore. 

In reply to bobzilla :

That's basically the "big standard". NC Miata uses it too, and I think that's the bore used by most aftermarket wheels which is then stepped down by rings for the hubcurious. 

SVreX (Forum Supporter) said:

I think the odds of shearing a lug bolt are significantly reduced when there is no movement against the studs because the center of the wheel is held firmly in place by the axle hub.

First: Once torqued, the wheel is held firmly in place by the axle hub through the face. The only way for that to not hold true is if the lug nuts come loose. In which case, yes, at that point there would probably be *some* initial benefit to the studs from the 'hubcentric' interface.

Second: If the lug nuts do come loose, the wheel is not held firmly in place by the axle hub through the hubcentric lip/bore. It is a slip fit. While it limits radial movement enough to keep the wheel off the studs at a standstill, it is not eliminated. It also does little to limit rotational movement (and impact forces against the studs) from any acceleration or braking force. And the looser they get, the less it helps.

Other than the lug nuts, the only thing that makes a wheel feel like it's being held 'firmly' in place, is corrosion between the mating surfaces.

Consider: If you have 1/2" studs torqued to 100 ft-lb, each stud is providing 4,000 lb of clamping force. With 5 studs, that 20,000 lbs clamping force. With a 0.6 coefficient of friction for an aluminum-steel interface, you would need to exert 12,000 lb per wheel to get the wheel to slide on the hub. For 4,000 lb of car/people with 60% weight bias, the most heavily loaded wheel is carrying 1,200 lb of weight. Thus it would take a vertical impact force of greater than 10G to cause any relative movement between the wheel and hub... If that occurs, you've got bigger problems to worry about than breaking a wheel stud.

Driven5 said:

SVreX (Forum Supporter) said:

I think the odds of shearing a lug bolt are significantly reduced when there is no movement against the studs because the center of the wheel is held firmly in place by the axle hub.

First: Once torqued, the wheel is held firmly in place by the axle hub through the face. The only way for that to not hold true is if the lug nuts come loose. In which case, yes, at that point there might be *some* benefit to the 'hubcentric' interface.

Second: If the lug nuts do come loose, the wheel is not held firmly in place by the axle hub through the hubcentric lip/bore. It is a slip fit. While it limits radial movement enough to keep the wheel off the studs at a standstill, until the lugs loosen enough for the bore to extend past the lip, it does not eliminate it. It also does little to limit rotational movement from any acceleration or braking force.

Other than the lug nuts, the only thing that makes a wheel feel like it's being held 'firmly' in place, is corrosion between the mating surfaces.

Consider: If you have 1/2" studs torqued to 100 ft-lb, each stud is providing 4,000 lb of clamping force. With 5 studs, that 20,000 lbs clamping force. With a 0.6 coefficient of friction for an aluminum-steel interface, you would need to exert 12,000 lb per wheel to get the wheel to slide on the hub. For 4,000 lb of car/people with 60% weight bias, the most heavily loaded wheel is carrying 1,200 lb of weight. Thus it would take an impact force of greater than 10G (from the car) to cause any relative movement between the wheel and hub... If that occurs, you've got bigger problems to worry about than breaking a wheel stud.

Agreed.  If you have wheel movement, the lugs aren't torqued properly.  Lugs are overkill and provide far more clamping force than necessary for 90% of the driving you'll ever see.  Baja trucks?  Yeah, I'd keep them hubcentric, but it takes more than an autocross course or a pothole to overcome lug clamping forces.

Are these autocross wheels, as in they'll be getting taken on and off a lot? If so I'd run centering rings (metal, not the worthless plastic ones) just because it makes wheel swaps a bit more convenient. Otherwise I wouldn't worry. I think I'm at like 75k miles on my fiesta without centering rings (and a few thousand before that with plastic rings that liked to adhere themselves to the hubs, get deformed, etc) with no issues other than wheel swaps taking a bit of extra effort to get everything lined up and usually an extra round of torqeing to get everything fully tight. If I was swapping wheels regularly I'd try to find some rings for them, but for the 2x/year swap between winter and summer tires I just live with it.

I agree completely with everyone who says wheel movement= loose lugs. 
 

But we've all seen lugs shear. 
 

So, I see no reason NOT to also use the hubcentrics. It's cheap, and painless. I've never sheared a lug. 
 

Not using them sounds like the same logic that would say "You've lightened the car. The maths says you don't need 5 lugs anymore. You can just use 4"

Yeah, but...

thedoc said:

In reply to John Welsh :

John, thanks for all the information.  The new wheels are Enkei.

I'm gonna guess that the Enkeis have a center bore size of 73mm.

Research says that a '06 Mustang has a center bore of 70.3mm

Therefore $9 via Amazon and free return shipping if I'm wrong. 

You might not have to have these rings but at $2.25 per wheel, they are too cheap to not have.  And, having them will help to assure a non-wobble fit.  

SVreX (Forum Supporter) said:

I agree completely with everyone who says wheel movement= loose lugs. 
 

But we've all seen lugs shear. 
 

So, I see no reason NOT to also use the hubcentrics. It's cheap, and painless. I've never sheared a lug. 
 

Not using them sounds like the same logic that would say "You've lightened the car. The maths says you don't need 5 lugs anymore. You can just use 4"

Yeah, but...

You're right that there's no reason to specifically avoid them, just no real reason to feel compelled to use them either.

FWIW I've definitely seen hubcentric wheels shear lug studs. Two on the same wheel, even. There was definitely some movement happening there one way or another.

In reply to dps214 :

Loose lug nuts.  It overstresses the remaining studs.

On trucks the general rule is, if one stud breaks, replace it and its neighbors.  If two studs break, replace all of them.