It is possible that your brakes are sticking. After driving for a while, smell inside the wheel and see if you can smell burning hot brakes. My guess would be that your wheel bearings have no grease in them. The best way to tell is to take the hub apart. To do this you will need various dental picks, some snap ring pliers, a hub nut socket (which you can rent or buy at most autoparts stores), and some patience. Its not really very complicated, just put everything back in the same way it came out. Make sure that you dont get any dirt in the hub whatsoever when you put it back together. Also be sure to use high temp wheel bearing grease (I like to use valvoline durablend semi-synthetic or full-synthetic grease). If you do determine that it isnt the brakes sticking and that it is the wheel bearings, you need to get that fixed asap. Dont go fourwheeling tomorrow!!! Driving without grease in the hub can cause serious damage to your truck and even you. With no grease, the wheel bearings can sieze to the spindle, resulting in not only you having to buy a new spindle, but it is possible that this could make your wheel fall off, in turn, endangering your life!! You need to get this fixed immediately. If your hubs are getting as hot as you say they are, you will more than likely need new races too. These need to be pressed in. If I were you, I would do this before I drove the truck anywhere again!
-Harrison
