You can run up to 33" x 12.50" tires on stock wheels with no leveling kit and no rubbing. If you have aftermarket wheels with negative offset then you might get rubbing and need to do the PW mod. I didn't put a leveling kit on my truck due to the number of people with leveling kits who have had their front axle shaft pop out of the differential. Very few people with stock Titans ever have this problem. If you read the front axle failer thread, you will see that the vast majority of people who reported their axles popping out had leveling kits on their trucks. That being said, there are lots of folks with leveling kits that have had no issues; however, every person I know who had their axle pop out of the front dif has a leveling kit, and nobody I know with a stock Titan has had this problem. I'm going on 6 years with no issues (knock on wood), and I thrash my truck like it owes me money. IMO, installing a leveling kit is not worth the risk of ruining your front dif.