Last time I dynoed I hit 554 with stock tires once and the rest were in the 530s and torque was around 970s then I put my 37" tires back on and hit average of 530s for hp and I actually hit 1121 for torque. I was surprised I fiqured the tire size difference would have been alot different. I gained alot of torque by the bigger tires must have been because of rpm range. I would just keep the tires that you have on. It didnt make that much of diff for me any ways.