Getting a wheel warranty honored has been a problem for many Mercedes owners. If you go the the MB forum you can read about many cracked wheels and corrosion problems and Mercedes not being willing to warranty them. They claim the user hit a pot hole etc for cracked rim and cleaned them wrong etc for corrosion issues. They have a 2 year limited warranty against defects.

Usa rims has a warranty that's the same as all the other aftermarket wheel makers. they warranty for correct fitment for your car and you must return them with in 7 days or pay 15% restocking fee. Like all wheel manufacturers once they are mounted they are driven on they are yours because you cannot prove you didn't hit a curb at 100MPH etc.. That's what car insurance is for if you have a bent or broken wheel etc you can make an insurance claim. That's especially helpful with very expensive rims but depends on your deductible and insurance company.