Is this "normal" for tires? Is the tire shop full of it?

"seems" is the right word. There is some tearing on the inside (engine side) of the lugs as well, just not as much.

 

Any chance you might be doing u turns fairly often on rough surfaces? I used to see this type of wear on our taxis as they often did u turns on local streets to save time. Perhaps you turn around in a driveway more than usual?

That one picture appears to be a cut. Probably a sharp rock or rough pavement did that at slow speed.

 

I back up a small trailer once or twice a week. Wouldn't the other tires show something similar? I've been good about rotating.

 

The tears look like 'normal' wear after lots of dirt roads. The dry rotting type of cracking seems odd though. Especially for tires that are supposedly only a few years old.

 

Depending on the surface you are backing up on and how much steering you have to do it’s quite possible this accounts for some of the damage. Slow speed turns really put some wear on tires especially if there’s a heavy load or sharp turning. If you turn the steering wheel without the tire rolling it will grind rubber right off the bottom of the tire.

But why just one tire shows this is beyond me. Unless you’re half on dirt and half on pavement often.

If the tires are all similar age and type I’d be looking at how the truck is used and whether it’s aligned before blaming the one tire. Driving on fire roads also could be the culprit.

As far as the dry rot cracking it’s not unusual especially if the truck is stored outside or comes from the South.

 

That doesn't look right to me, but I'm not expert.