Brand new 2008.5 Titan SE CC Standard Bed w/Tow Package. P rated 18" tires (passenger tires correct???). On my last tow vehicle (Dodge van) I replaced the passenger tires with light truck tires (LT). Will tow a 25' Airstream (7300lbs GVWR most likely I'm at 6000lbs). Have Prodigy brake control and Reese WD/sway control. If you all suggest new tires would a dealer take trade on tires w/ 300 miles???