Hubcentric Adapter

For years car enthusiasts have used spacers to accommodate wheel offsets that the wheel manufacturer's did not or could not offer. Wheel spacers, for various reasons, they have been maligned as compromising the integrity of the wheel to hub mounting union.

Wheel manufactures have now produced "hubcentric wheel adapters" as Ronal identifies their wheel "spacers". The following address the question. Are these "hubcentric wheel adapters what the manufactures claim they are, i.e. a structural extension of the wheel backing with full hubcentric load bearing function? Or are they simple wheel spacers with a new name?

Having installed wheels and tires using this hubcentric adapter system it seems appropriate to examine exactly how this system functions.

The photograph below shows a Ronal hubcentric adapter (blue arrow) installed in one of their wheels. Note that the wheel has to be manufactured for this adapter.

Removing the adapter shows that it's manufactured with a "lip" (blue arrow) that fits tightly inside a corresponding machined opening in the wheel (red arrow).

Re-installing the hubcentric adapter on the wheel revealed that there was no lateral movement between the adapter and the wheel. This is important, because Ronal claims that these adapters are hubcentric to the wheel, i.e. an integral part of the wheel.

Examining the front hub (photograph below) identifies the part on the hub that the adapter fits around. Note that the load bearing part of the hub is only approx 1/2 inch wide. (blue arrow), and raised slightly from the rest of the hub.

Looking at the adapter next to the hub it's apparent that the adapter is designed to fit over this load bearing part of the hub.

When installing the adapter on the hub the adapter is initially larger than the hub until the last 1/2 inch. At that point there is an identifiable fit as the adapter is installed over the last 1/2 inch of the hub. This is the load bearing part of the front hub.

When held flush against the hub so that the adapter fits over the load bearing part of the hub, there is no perceptible lateral movement of the adapter.

As the photograph below illustrates, the adapter is hubcentric to the hub. Note the even space around the wheel lugs (blue arrows). This indicates the adapter's load bearing function is at the hub, not the wheel lugs.

My conclusion: Hubcentric adapters, when designed and manufactured properly to fit a specific wheel, do maintain load bearing at the hub. As illustrated in another link in my website I currently have these wheels and hubcentric adapters on my automobile.



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