Wheel backspacing ?

[slck6t9]

I know this has been asked a thousand times. I just sold my 16 inch TTII's and am wondering what backspacing I would need for some 17's. They will be 17x8 in the front with factory disc brakes. The rears will be 17x91/2 with stock drums. Does the drum brakes make a difference on the backspacing because someday I would like to add disc on the rear. Also what would the max sizes and backspacing be for some 18's. Will I need to roll the lip on the rear with 17 x 9 1/2? Thanks


Scott