Can someone explain this to me? What are the differences? Why are there differences to begin with? Why not just do one or the other on ALL cars?

Thanks in advance!

 

This is just info that I've picked up. I apologize for the lack of technicality and if I'm wrong, someone please correct me.

Hubcentric basically means that the hole in the center of the rim fits exactly on the hub of the car. If it's slightly larger, the wheel may not sit balanced and you'll get some serious vibration at highway speed. When the wheel is hubcentric, you put it on (while the car is on a jack or jackstands), hand tighten the lugs, put the car down (allowing the weight of the car to be on the hub), and torque down the lugs in the suggested star pattern.

When your wheel is not hubcentric, you then have to rely on the lugs to keep the wheel centered so you don't end up w/ the harsh vibrations at highway speed. When you put on lugcentric wheels, follow the same installation process for the hubcentric wheel except that instead of putting the car down after hand tightening the lugs, leave it up, and torque in the star pattern.

So basically, hubcentric relies on the hub for weight distribution and centering of the wheel, and lugcentric relies on the lugs and its hardware for weight distribution and centering of the wheel.

Not all car manufacturers have a standard sized hub. Therefore, wheel manufacturers will make the center hole slightly larger in order to fit on more than one car/manufacturer. If the hole is slightly larger, a hubcentric ring can be bought. It's just a ring that fills the gap between hub and wheel.

 

That's pretty close, here's another way to look at it. First off, hubcentric wheels are always preferred. All wheels that come OE on cars are hubcentric - ie. the centerbore of the wheels perfectly fit on the hub. The reason this is usually preferred is that lugs are usually tapered and any imperfection in any of the tapers or the stud integrity will pull the wheel slightly off center.

Aftermarket wheels are usually drilled large so they will fit a number of different cars. To still make a wheel fit hubcentric (ly) then a "centering ring" is used. These rings are often made of plastic or aluminum - so torque them while the car is up because you don't want to squish the ring.

Either way - all wheels sold by The Tire Rack are either hubcentric or made hubcentric by using a centering ring. Most of our wheels for Subaru are drilled hubcentric because the Subaru bolt pattern and offset are unique compared to other manufacturers but greatly similar within the Subaru brand.