427Z

did GM change OEM? if so, when, and is one better or lighter wheel than the other?

vegasdude

THe ones that you don't have are usually the better ones.............

Exterminator

Isnt' that the truth!

427Z

i had a set of both. i sold the USA ones just now because they were comp grey and kept my polished ones. i did this based on color but was wondering what the story is behind the OEM change.

so...did i sell the wrong wheels?

Knooger

According to post #2 you did sell the better set of wheels.

dpglusko

GM supposedly switched to Speedline as their vendor for at least the Z06 Rims for the '07 model year. The Italian Speedline wheels require less balancing than the previous USA OEM rims which would indicate an improvement in manufacturing tolerances. I can't speak to the finish differences as I have only seen the chrome rims on my LMB '07.

allanlaw

I think the ones marked USA, like mine (early production '06) were made by Amcast. Amcast went belly up mid-year, and GM took the tooling (which they owned) to one or more other suppliers, one of which is clearly Speedline. Whether one is better than the other, lighter, etc. is just guesswork, but since they come from the same molds and are probably based on the same specs, I doubt it.

427Z

thanks guys. i know when speedline italy took over the C5Z wheel production in 2002, their cast wheels were a little lighter (1-2 pounds) than the 2001 forged Z06 wheels made by alcoa.

i guess the weight difference was due to cast vs forged. also, speed line used slightly fatter spokes than the alcoa wheels on the C5Z, so they didnt exactly use the same molds.