I just installed new wheels, which are lug-centric, and I have a slight steering vibration I just can't get rid of. The wheels are perfectly balanced, and use the proper hub centering rings for the car. But those are cheap plastic ones...so my question is: should I fully tighten the wheel nuts when the car is off the ground, because I think my vibration is caused by the fact that when I tighten the nuts with the weight of the car on the wheel, like when using hub-centric wheels, the plastic ring gets out of shape, resulting in an off-center wheel mounting, causing the vibration.

Am I making any sense???

thanks

 

Not familiar with the term "lug-centric" unless that means the wheels are supposed to center themselves with the tapered end of the lugs for positioning? Anyway, the way I've always tightened my wheels regardless of their style has been to progressively tighten them in a pattern across from each other and then in a rotational pattern...all the way to the point where I cannot tighten them anymore without the resistance of the ground contact. You can even spin the tire as you go through this routine if you think the weight of the wheel is tending to "set" things slightly off. Anyway, I then set the car down and tighten to the proper torque in the same manner.

Don't know if this response was of any help...hopefully so.

 

I've done my homeworks...

All wheels are classified as being either "Hub Centric", or "Lug Centric." The term Centric refers to the way a wheel is centered.

In other words a hub centric wheel (i.e. OEM wheels) centers on the hub of the car, if you put the wheel on the car without lug nuts the wheel would be perfectly centered.

On a lug centric wheel (most aftermarket wheels), the wheels are centered by the lugs as they are tightened down. Manufacturers build wheels lug centric to allow the wheel to fit a wider selection of vehicles. The center bore of the rim is bigger than the hub on the car side. Conical lug nuts actually are what center the rim on the hub. This design is widely used because of ease of manufacture. Also, there is not that much precision needed while machining the hub-center in the rim (sometimes it is off-center a bit...).

Hub rings serve no purpose after installation, their entire job is to hold the wheel perfectly centered while the lug nuts are being installed. The hub rings sole responsibility is to take up the space between the center bore of the wheel and the hub of the car.

The most common cause of a car vibration is a wheel that is off center slightly. For example, with lug centric wheels vibrations commonly occur when an installer tightens the lug nuts incorrectly, such as when they tighten one side before the other the wheel can be "pulled" to one side. This common problem could be prevented if the correct hubring was used during installation.

While a lug-centric design seems more versatile, it has a few drawbacks. There is not much of the wheel that touches the hub. Where the conical nut resides is raised more than the rest of the wheel. The rim only touches the hub directly around the bolt holes. Because of the nature of the centering device (the lugs), lug-centric wheels should be torqued correctly while the vehicle is still off the ground so they center properly. The weight of the vehicle can push the wheel off-center slightly while they are being tightened if left on the ground. If the wheel is not properly centered, a vibration can be introduced through the wheel.

Here is the correct installation procedure:

Step1: Place wheel on studs and flush against the hub. Using the conical lug nuts, thread them onto the studs by hand until the wheel is snug (do not use impact wrench).

Step 2: Use a high quality, calibrated ratcheting torque wrench. Set the wrench to 25lbs. On 5-bolt hubs rotate one fastener to the 12-o'clock position. Torque it to 25lbs. Then go on in a "star pattern" for all lugs.

Step 3: Repeat this procedure with the torque wrench set to 50lbs.

Step4: Set the torque wrench to 75lbs. and repeat the sequence. Do not lower any of the weight of the car onto the wheels until they are completely torqued. This technique applies an incremental clamping load to the bolt circle, in order to avoid rotor or wheel warp age.

Step5: Re-torque the fasteners after the first 75 miles.


Hope this has been helpful a bit...

P.S. : when getting lug centric wheels balanced, since the hub-center can be a bit off, you want a shop equiped with these: http://www.hawekana.com/Pages/Haweka_FlangePlate.html

 

I wish i read this post before I put my snow tires on yesterday. Very helpful!