I can't really help you with your tire question but I just recieved a leveling kit for my Titan. There are two reasons to put one in. The first is looks. Some people do not like the drop nose look the 04 to07's came with. The kit will raise the front end level with the back. The second reason is tire clearance. When you lift the front end you allow the mounting of a larger diameter or wider wheel and tire combo. Obviously you still have to be careful with rubbing and clearance issues. You will need to pay attention to the rims backspacing and offset and keep everything reasonable. Read through some threads on here and you'll see what I mean. I bought the PRG leveling kit based on recomendations on this and other sites. I am having it put in wednesday and can't wait to see how my ride looks. Good luck and welcome to the forum.