you can easily run 35" tires, but on your stock wheels 285 is the widest you can go to guarantee no rubbing. Some people have fit 295's with no or minimal rubbing but then some trucks needed 1/4" spacers with 295's
Just to try to keep confusion down, it appears that 2013's and 2014's can fit wider tires on stock wheels with no rubbing. I'm saying this because you have a 2012 and you will get responses from members with 2013's and 2014's
like said above if you get new wheels proper backspacing will prevent rubbing