Wheel question

[chlh]

I have a 05 Silverado with a 3" BL, 4" rear blocks and Keys. I am currently running 315/70/17s on stockers with 2" wheel spacers. If I add on a wheel with a -6mm offset and 4.75 backspacing, how far will they stick out. I have the stock fender flares and am trying to go for a more aggressive look and wider stance. Thanks and send pictures if you have this set up

[chlh]

Need help ASAP ordering the wheels tomorrow if they will give me a wider stance.

[burt]

first thing would be to find out what the backspacing is on your stock wheels. then compare that to the ones your looking at