I have a little S10 & I've got 315/35-17s in the back w/ lakewood traction bars. My rear is a Zexel Torsen posi from an LS1 camaro.. I'm sure since your truck weighs more you should be fine but w/ all that extra power comming I'd suggest some traction bars to help out.. after all it's a pick up & there's still not a huge amount of weight back there, right? heh