On the '03 the lug nuts are 15/16" and I'm assuming the 3rd Gens are all the same -- but any reasonable mgr at a Napa, Pep Boys, Kragen, Shucks, Checker, etc. should have no objection to you taking a socket out to the parking lot to make sure. Be sure to buy a "deep" socket, and if you don't already have them, buy a 10" to 12" extension and a 14" to 16" breaker bar. If you have a quad cab all three pieces will lay nicely in the little space at the base of the rear cab wall underneath the bottom of the left-hand rear seat. Everything should be 1/2" or larger; 3/8" doesn't have the muscle to get those nuts off after they've been put on with an air wrench.