Is it Supercharged? If it is, you can't fit a 19" Wheel over the Brembos. The '10 and Newer need the 20" Wheels if you have the 15" 6 Piston Brembos. If not, I second either giving up the 20s or the Terra Grapplers. I loved them on the F150 I had and I'm thinking about putting them on my Full Size now.
"I have taken more good from alcohol than alcohol has taken from me." - Winston Churchill