Tires for a 2015 bighorn 4x4

[bgas]

Good afternoon all, i have to replace the tires on my ram shortly. I am trying to put some larger tires on my 20 inch rims and am looking at some 305x55x20 Falken tires, and I plan to put a 2 inch level kit on up front. My question is what is the biggest tire I can put on the stock rims without them rubbing on the inner fender or sticking out of the wheel well? Any suggestions if I can go bigger than the 305x55x20s? Thanks for your help, I appreciate it.