Will they fit?????

I got a pretty killer deal at the tire shop and bought some 20's for my 2004 ex. cab silverado. I didnt pay much attention to the offset etc when I got them but I want to know if its possible to make them tuck on my truck.

They are 20x8.5x5.5. If they will tuck what size tire do I need to make them tuck and will I need to roll the wheel wells? Thanks guys.