2014 silverado crew cab vibration

[donc]

My truck has 55,000 miles on it, new firestone le3 tires at 47,000 mi., compared to the original SRA tires the le3's felt a little harsher on bumps but smooth and quiet overall.  Shortly after I rotated the tires I started noticing something like a harmonic vibration, more noticeable between 30-50 mph and depending on the the road surface.  Took truck to chevy dealer, had tires rebalanced , front end alignment checked and they ended up rotating the tires again, its still vibrating. Going back to tire dealer next week because I think its something with the tires, even tough the tire surface is pretty flat. If I put the truck in neutral the vibration stays the same  that's why I'm pointing at the tires, but is this logic wrong? the vibration feels like I'm driving over a very mild form of those slots they put in the center of the road or if your driving with a rear window open where you get that pulsating noise / feeling. Anyone have similar problems that might be something look at, I appreciate any feedback. I drive very easy on my vehicles, avoid potholes, nothing off road, things like that  so pretty I'm confident its not a damaged part situation.

 

Thanks, Don c.

[mikeyk101]

Did they just do a standard balancing or did they do a road force balancing? I know on my OEM Goodyears, I had a vibration problem that finally got solved after the dealer did a road forced balancing. I don't remember all the technical details but one of the 4 tires was off and the road force balancing got it corrected.

[donc]

Thanks, I'll ask about the balance, I'm not sure how they did it. I'm used to talking to the service manager or mechanic themselves, in this new world you don't get to talk to anyone close to the work anymore. I crawled under the truck today and checked the universal joints, they all seemed tight except the output shaft to the front wheels on the transfer case had some play in it right at the case, I'm assuming there's a bearing inside close by, kinda surprised me because I've only used four wheel a couple times over the years, although I engage it on straight runs once in awhile just to move things around. i can't see how that would contribute to any vibration but on the other hand I'm assuming there's rotating members in that case and something could go wrong in there. I changed that oil last year, along with every other fluid in the system.

[Sjwoei]

Road force balance all tires. It detects hard spots in tire that normal balancing wouldn’t catch. When they replaced your tires they probably put the one that balanced out with the most weight on the back so it would not be as noticible but now you’ve had a rotate and it is noticible