Update: in Spartanburg, SC this morning, Firestone says the other Firestone used the wrong weights (this is now 4 shops in a row saying the wrong weights were used by previous shop), and says the right rear tire is bad, it's oblong. Discount here is closed on Sunday (where I bought the tire). Going to see if I can find someone open that has one in stock and hope discount will reimburse me.

 

Thought I would give a final update on this. Left the Firestone in Gulfport, MS and the truck still vibrated like hell. Made it to Spartanburg, SC where another firestone said the right rear tire was out of round. Found a replacement tire in stock at a local Sears and had the Firestone mount it (because I was going to kill the useless sales guy at sears). The replaced right rear tire made a huge difference but the vibration remained. Made it to Asheville, NC and Richmond, VA, didn't have time to deal with it at either of those places. Called a Discount Tire in Raleigh, NC when we were headed south from Richmond, told them this entire story from top to bottom and the manager said "Bring it in, I'll replace all four tires."

Next morning I pulled in, they pulled the truck in, swapped out all four tires and it now drives and handles like an entirely different truck. Smooth as silk (well as smooth as a 3/4 ton truck can be) and it's driving manners are entirely different and way better at all speeds. All four tires were apparently bad. Who knows what was actually wrong, but given that the tires stunk like hell when I got them originally and that the truck truly handles differently now, I'm going to guess they were not cured correctly. I had every plan to make discount pay for the tire I paid out of pocket for, the extra balancing I had done chasing something they couldn't figure out, but the no questions asked replacing of four tires by the shop in Raleigh was too good of customer service to beat the guy up on (especially since he didn't sell me the tires). I'm back in San Antonio today and do plan on stopping by the Discount that sold me the tires and letting them know how I feel.

Tires aren't made four at time... there's little doubt in my mind that there are other people out there having fits with these tires, probably a bad batch. Be interesting to see if other issues pop up around the web.