First, I would get the wheels balanced. The wheels might be balanced, but when you put tires on them you need to have them rebalanced.
Second, get the hubcentric rings.
http://www.gorilla-auto.com/
Pg 44 (part 2 of catalog)
or try your local wheel dealer.
THe Alero hub is 70.3mm
Third, you may have warped rotors.