Wheel spacers question

[DSmith78]

Have a 96 gmc sierra 4wd. stock wheels eventually gonna put 285 tires on. would like to run wheel spacers. to me its looks like the back wheels sit in further then the front. am i wrong thinking that i should run 2 inch spacers on the rear and 1 or 1.5 on the front? did a search and found alot of useful info but no real answer to this. Thanks

[1997SierraSLT]

OEM wheels have same offset front and back. 265/75/16 tires came standard on the K1500 models if not mistaken. Going to 285 series tires on OEM wheels should work fine with no interference issues.