what is the centerbore of the 928 wheels?
#2
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about 60 MM with a very cheap caliper and since Porsche wheel are hub centric that dimenesion is VERY important. The lug nuts hold the wheel against the hub but the hub locates the wheel AND takes all the load. Too large a hole and the lug nuts are subjected to shear loads far beyind their design. If the wheel maker does NOT know the Porsche specs odds are they do not have the ability to make a correct wheel.
#3
Three Wheelin'
On wheels I've measured it's 2.8217. The hub register is 2.814. It's good that you're asking, a wheel that doesn't fit over a hub register WILL have runout as well as be less sturdy.
#4
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Thanks Mike for the real numbers !! My daughters Pantera the custom wheels were too tight and it was nearly impossible to get the wheels off !! Not a GOOD THING ...
#5
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I go the same measurments within a few thou of an inch. That equals:
71.67 mm wheel
71.48 mm hub
So, that's 0.2 mm clearance between wheel and hub. Also, the concentric hub leading edge is beveled to guide the installation. The hub protrudes about 12 mm beyond the mounting surface. Any flat spacer beyond 6 mm will not allow the wheel and hub to engage, and even then, the engagement is not as full as original.
The lug seat and lug nuts are dished and fit snugly, so there is accurate centering there, but I gather there is not enough strength in the lugs according to what Jim reports. Guess I'll discard those 12 mm non-hub centric spacers I got somewhere.
71.67 mm wheel
71.48 mm hub
So, that's 0.2 mm clearance between wheel and hub. Also, the concentric hub leading edge is beveled to guide the installation. The hub protrudes about 12 mm beyond the mounting surface. Any flat spacer beyond 6 mm will not allow the wheel and hub to engage, and even then, the engagement is not as full as original.
The lug seat and lug nuts are dished and fit snugly, so there is accurate centering there, but I gather there is not enough strength in the lugs according to what Jim reports. Guess I'll discard those 12 mm non-hub centric spacers I got somewhere.