Hi, I just bought 2 used IROC wheels and noticed something odd about the bolt holes where the lug nuts would seat. I thought all of these wheels have purely the conical seat, however these 2 seem to have been machined to have a flat washer also. See photo. I measured that the machining has removed about 2mm of the aluminum around the bolt hole. Would this weaken the wheel enough to be a concern? Any idea why this would be done?

 

Not a factory gm wheel its for something else. Is the bolt patterm evem correct?

 

It looks identical to a factory 88/89 IROC 16x8 aluminum wheel....never seen a reproduction of those years...

 

A repro would still have the tapered seat. Thats not a iroc wheel of anykind must be something really close. Still curious f it haa the righ t bolt pattern

 

I checked the bolt pattern and its the same...fit right on.