Im looking into some new tires and rims since my tires are going. Im having trouble understanding offset and backspace. I want them the stick out a little bit from the wheel well so what offset and backspacing should I look for when buying? Also one more thing I have stock 17in rims im looking at getting 18x8.5 what size tire would I get for it to be a 33in tire?

 

Basically, the more backspacing a wheel has, the more it tucks in. A common aftermark spec for an 18 inch wheel appears to be 9 inches wide with 5 inches of BS. This means the wheel will stick out 2 inches farther than your OEM wheels. Another commom spec is 9 inches wide with 4.5 inches of BS which means the wheel will stick out 2.5 inches farther than the OEM wheels.
As for a 33 inch tire, 285/65-18's (33x11.50) and 325/60-18's (33x13.00) are the two most common sizes, but a few 305/60-18's (33x12.50) are available.