For years now one of the trademarks of a first class SCCA Trans-Am, or IMSA GTO car was the centerlok wheels. Just by a glance at the wheels you could tell who was a serious contender, or a pretender. Generally those wheels were made by BBS, although Jongbloed and a couple of others were occasionally seen.

What was the reason that the centerlok, more properly center knockoffs, rather than the almost universal 5 x 5 pattern wheels were used? Basically there were three reasons.
1. Unsprung weight. The suspension components and hubs were lighter than on an equivalent 5 x 5 assembly.

2. Suspension geometry. Most designers are proponents of the “zero scrub” design. This requires getting the wheel mounting flange as far outboard as possible. In other words a typical three piece centerlok front wheel will have a 1″ or 1.5″ outer rim half. Because of its spindle design a 5 x 5″ wheel has to use a wider outer rim half, perhaps 3.5″ or 4″.
3. Pit stops. With the single nut, the time to change tires was less. Admittedly this was the least important of the three factors.

But nothing is without drawbacks, and this is no exception. The price of a centerlok suspension assembly is far more than that of a 5 x 5. How much, did you say? Well it varies but it is hundreds of dollars per corner. Wheels for the 5 x 5 are far more readily available and at a fraction of the cost. And lastly since most races no longer require pit stops the speed of tire changing is pretty much irrelevant.

I should note that there is a hybrid design, used back in the 90’s by Peerless and a few others that adapted a 5 x 5 hub to use centerlok wheels. This was neither fish nor fowl, didn’t solve the geometry issue, and added about one pound of weight per corner.

So which is the right way to go? Depends on your wallet I guess. If money is the most important thing than by all means go with the 5 x 5. But if performance, and looking the part, are critical than the centerlok is still the way to go.

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