phillyturbosix said:
The GNX rims are stamped front and rear. The GTA rims are also all stamped front or rear. When buying GTA rims you always want the dimple style. The reason GM made the dimple style is because the non dimple style rims the center hub was too weak and were famous for cracking and opening up when you installed or took tires off of them. Tons of people would get new tires and find the center caps no longer stay on the rim and just fall off. So the dimple style came out with a more hardend center hub. I guess GM added the dimple so they knew what was what. There was also a good number of companys that made GTA look a like rims.
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http://www.turbobuick.com/forums/showthread.php?t=190452&highlight=GNX+rims
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Jim:
Real GNX rims were identified with the numbers -17 & -23, representing rear & front offsets, respectively, in metric. I don't beleive that either one carried the term "front" or "rear", and were further identified with the manufacturer's trademark, and maybe molding codes for dates, times, shifts, & so forth.
Real GNX rims were not dimpled, and were not known for cracking. At least I have never heard of any real GNX rims cracking or seperating. On GTA rims, I believe that up through '85 or '86 they were not dimpled, and '86 or '87 and upwards they were dimpled, and less desirable than the non-dimpled GTA rims. Some people have even been known to fill in the dimples for that "Re3al GNX look". I have never heard a specific reason as to why the earlier years were not dimpled and the later years were dimpled, but it would be very doubtful that the manufacturer, who I believe was JLL industries, or something like that would go to the trouble of using the dimples only to signify a different manufacturing process. The different manufacturing process were 1 piece, and 2 piece, and I do not remember which was which. Real GM center caps are not known for falling off, but all, or most of the center caps that fall off are aftermarket made in maybe Taiwan, and are made too small in the area of the mounting dimensions, and therefore fall off of the front rims when the rims expand due to the heat generated by the front brakes. I will not say who imports the aftermarket caps. The replica caps would most certainly stay even on the front running the factory spring wire clips designed for such. You have a good laugh coming as I unfortunately, learned all of this the hard way. Good luck in the upcoming East Coast blizzards, though.