What are the bigest size tires i can put on my stock 2004 chevy 2500HD with out any tire rub. In the near future I am planning on putting a cognito leveling kit on it. Thanks any help will do.

 

You can generally go up about 2 numbers in size without problem. Example, if You have 245x75x16, You can go to 265x75x16. They will be about 1" or so taller and shouldn't create any problems. Account for the change in your speedometer, it'll read a little less speed than You're going.