First post, after reading most of this thread: Purchased 2016 crewcab, 6.5' bed, 6.2L w/ 3.23's in September.
Came with 22's. Noticed shaking at 73 mph+ on drive home from dealer in Montana (I live in WA state, but found what I wanted in MT, a 6.2 LTZ w/ the 40-20-40 front seat to accommodate kidlets).
Took a video of the shaking water bottle (like we've seen so much of on Youtube) and sent it to my salesman-- he said take it in to my local dealer. I figured it was the wheels, and since I planned on replacing them I held off on going to the dealer.
Got the wheels replaced with 18's a couple weeks after purchase, with Gear rims and Michelin Defenders (LT 275's) and guess what-- the shake remained.
Took it into my local dealer, explained the symptoms in great detail, brought in a copy of the service bulletin, and even provided the video I took. Picked it up a few days later-- they had let some air out of my tires, folded up my tonneau cover, and said "it's much better."
It wasn't.
Went back, and got the "it's a truck, they all do that. In fact we drove two others on the lot, and yours is better."
I told them this was unacceptable, so they had me come back in and they did the Pico test. They also ran the test with a different set of wheels, and according to the readout (which they provided a copy of) it was better, conveniently within spec, with the different wheels ( a set of 20's with Continental P tires that they had taken off a new truck).
I took my wheels back to the tire shop, and they did a balance, then a RFB, neither of which produced a discernible change.
Back to the dealer with a request to drive the truck with the 20" Continentals. It seemed a little better initially, perhaps due to the fact that they're P tires and not LT's. But there's still a vibration, though like many, it's somewhat intermittent.
So now what??? I asked the service manager to do the tests they line out in the service bulletin, but he said the first thing Chevy asks is if they've done the pico test, and if it's within spec, they won't authorize any more work.
I've called GM direct, much to the chagrin of my dealer, and have a case number going. I'm going to press for doing the tests on the drive shaft, ring and pinion, etc-- we'll see.
I understand the dealer is under GM's thumb, but it really pisses me off when they pass it off saying they all do it because the frame is so stiff.
My questions: Has anyone put airbags on the rear suspension? I understand this would only mask the symptoms, but I'm okay with that. I thought about the Sulastic shackles, but I believe Abominable tried that to no avail.
Has anyone tried different struts (or whatever they are) in the front? Again, masking the symptoms, but I'd take it.
I'm struggling with the notion that LT's would be worse than the P tires-- it seems the stiffer tire would simply transfer more road roughness, but anything originating from the truck wouldn't be affected. Maybe the slightly rougher ride from the LT's would just make the vibration seem worse.
Any help is appreciated-- I've never been more excited and then disappointed in a purchase!!