Want to put off road tires on my 2003 Z71 Silverado truck, what sizes wheels can I put on without lifting it?

I currently have a 2003 z71 silverado with 20 inch rims on it with 285, 50 20 tires but I want a more aggressive look without lifting it, what combination of wheels and tires can I go with without lifting it, I'm looking at maybe 17, 18, 19, and 20 inch rims? My truck is 4 wheel drive too.|||i have a 2000 Z-71 and i have factory wheels 16X7 and the biggest i can get on mine with out rubbing is 285-75-16 if you go any bigger they will rub