1. Start off with something simple, and kinda fun in my opinion. Scrub down the truck, and give it a good wax. This is for more than just looks. For those of us in the rust belt, salt coats the underside of the truck, accelerating the formation of rust wherever it touches. Ideally you have already washed it a couple of times over winter. If not, get the hose out and completely spray the underside of the truck, with special attention to the wheel wells. After washing the truck, apply a good wax, any brand will do. This will help further protect your paint not only from rust, but also cracking clear coat due to intense sunlight.
2. Next is tire pressure. I am sure that you had to check it on multiple occasions over the winter. We know that with every 10 degree drop in temperature, we lose 1 pound of pressure. You may have to add a good 7-10 psi over the course of the winter depending on how cold the season was. Over filled tires have excessive and uneven wear, with most of the wear occurring in the center of the tread pattern. The only time you would want to have the tires over filled is under very heavy load conditions, like pulling a heavy camper. Many trucks spec a 20 psi difference between front and back because the rear tires can see extra stress while pulling a trailer. Always reference your owner’s manual for proper pressure specs.
3. Speaking of pulling a trailer, 15 thousand pounds is hard on your braking system, even with trailer brakes. A brake inspection will tell you the overall health of the braking system. Pull the wheels and look at the brake linings, any lining 2 mm or less needs to be replaced; it is important to know that the thinner the brake pads get, the faster they wear. All of the pads on the same axle should be within 2 mm thickness of each other. Front brakes do 70% of the work, and the rears do the other 30%, so it is easy to imagine that front pads wear faster than rears. Always replace pads on both sides of the truck at the same time.