CROY, if you feel you must change your tires, my opinion is to go with Goodyear G614's. You will need to verify that your wheels are capable of the increased air pressure of 110 psi. You may be able to trade in the tires on your new rig and get a good deal.
OR
Go with the tires you get eith the rig. The 2985 is the lightest of the Bighorn line. Keep an eye on your pressures and inspect the tires often. Check pressure before every time you tow both heading out and going home. Watch for bubbles on the tires.