You'll need some sort of spacer for sure. 1/4" atleast. A lot of guys are not a fan of spacers, esp large ones. Make sure they are good quality and not some cheapies off ebay. Because if they do fail, it won't be pretty.
It depends on the brand tire you get too... brands like Nitto run WIDE, like acutally 13/13.5" wide. As opposed to my 35x12.5 federals that are only 11.5" wide give or take.
do you know if I would be able to fit 35x12.50 on my 08 ram with 20" stock rims I have a 2" leveling kit and I heard that I would need a 1/4" spacer , I kinda wanted to put 1" or 1.5" wheel spacers on to have the wheels stick out a little more. thanks