you can have them bored out if you want to. but i ground the tabs off mine and used 1/4in spacers in the back. works fine and has been on there for awhile now. also i have the 205 40 tires by falken. i drive it everyday.
the stock lugs are 12mm and the gm holes are 14mm. what youll need are bulge seat acorn nuts for your 12mm studs and youll be fine. i got mine from my buddy at discount tire.