An 8.5" +18 wheel has a backspace of 5.5" which will tuck slightly more (1/4"?) than a standard z85 wheel. With an 8.5" wheel you are likely planning to run a wide tire. Chances are, you're flirting with rubbing. I'm assuming you are looking at a 265 or 275 wide tire.Will 20x8.5 with ET +18 work? I know they need bored. Off of 2003 seirra. ..custom wheels. Thanks..
4x4? 2x4? Stock suspension or lift/lowered?it is a 2010 crew cab. I have found a better wheel. It is a 5 spoke chrome on a silverado 20" 2009 . A friend that has a wheel and tire business said they will be alot better match but I do not know the ET spacing.