I really am humbled being on here. I appreciate so much of the knowledge. I don't so much mind the adapter acting as a spacer because its a look I wanted to achieve anyways. As far as the aluminum, I do plan on running in the snow, how long are we talking before the corrosions becomes risky? I wouldn't mind changing out every 2 winters or so but hopefully they last longer than that. Lastly, I don't see on the link for the adapters the measurement for the inner diameter of the adapter. I know the hub pilot diameter is 3.35 in. Should I essentially ask for 6 x 139.7 to 6 x 120 adapters with an inner diameter of 3.35in? Again, thank you all so much for the support
The corrosion won't as much compromise the adapter as much as make it very hard to remove or sometimes snap a lug. After a while, I ended up grinding a notch on each spacer so that I could fit a small chisel to assist removing them when I wanted to.
My brother who used adapters for wheels had a reaaaaaaaaaaally hard time getting them off recently. Due to the corrosion, his lug nuts were seized onto the adapter lugs. Stripped the nut clean. Had to drill off and ended up gouging the shoulder of the wheel, weld filled it and redrilled (they were rep Porsche wheels).
I would recommend using your stock wheels during the winter and the new wheels for all other times. Would benefit in that you don't damage the nice wheels with the winter salt and everything and don't have to worry about the adapters causing any problem. You could also run different tires for spring-fall use or off road or anything you want to do and have a better snow tire for the winter on the stock wheels. If you do use the adapters through the winter where salt is used, be liberal with anitsieze or something on the surface and possibly lug threads.
As far as the hub diameter goes, I have no idea what it actually is, if they were the same then that would be great but most times the adapter/spacer diameter is larger to fit more vehicles. With it being larger it can cause vibrations and put more stress on lugs.