I did oil change 06 GS430 myself today, I found there is a part missing, under the car. i am not sure is it normal? Or it's the reason makes the tire cupping? I really need your help, I am kinf of worry this issue now, thank you!

 

If I am looking at the pics correct its for the AFS and I think its only on one side of the car off the top of my head? So you are not missing anything if I am correct.

 

^ yup.. AFS sensor, it's only on driver's side.. not sure about cupping noise.. did you lower your car?

 

+1. Looks like the AFS sensor bracket. Def not causing the cupping. What kind if tires are you running? Alignment recently? How often do you rotate your tires? Stock suspension?

 

I use Falken ZE912, and everything is factory stock. Maybe I didn't rotate the tire that often (did it 10k or more) also got alignment done at West End; the tire has 50%~60% life left, I don't know should I just get another set of tires? Any suggestions? Thank you!