I bought a 2015 GMC Yukon Denali 4WD with 6.2L, 6-speed Auto, 3.42 Rear Axle, and Magnetic Ride Control on April 5th right after it rolled off the delivery truck. It came with the Touring Package which includes Denali stamped 20" chrome wheels. The OEM tires were P275/55R-20 Continental CrossContact LX20 with EcoPlus Technology. I had other warranty related issues, but not the vibration around 70mph.
Mid-May I ordered the GM CK156 (SEY) 22" Chrome Wheels along with the GM recommended associated tires - P285/45R-22 Bridgestone Dueler H/L Alenza. Received them and then had them installed Mid-June.
My wife and I drive daily on a highway with a speed limit of 70mph so it's easy to go "at least" that. In the first couple of days, we noticed the vibration as shown in the water bottle test. Scheduled an appointment with our local dealership to have them look at it. We just figured we lost a wheel weight. They ended up taking the wheels/tires to another dealership that "had better equipment" to remount and balance them. I didn't make any assumptions and just figured they were doing their due diligence to fix it.
Got it back the last week of June and the vibration at 70mph(ish) is still there. Googled "GM Vibrations at 70mph" and that's how I landed here.
For us, I was just looking into paying another shop that I know that has a RF to test and/or fix the vibrations with the assumption that there's still something off with the 1 (or more) wheels or tires; however, after reading this "book" / forum, I'm a little concerned that there might be a much, much, bigger issue going on. Still debating next steps / how much annoyance I'm willing to put up with with being in and out of the shop vice hearing the wife "tell" me about it every time I ride with her.
The only things that changed from no-vibrations to vibrations are:
- Different size/weight wheels
- Different tires (size, ratio, width)
- Tires not mounted/balanced from factory, or, according to GM policy, from an ADI (Accessories Distributor Installer) via the LPO (Limited Promotional Option) program
- More miles on the vehicle (a previous post noted that this started occurring a couple thousand miles into it)
The above differences could have an impact to other vehicle components, or it could be pure coincidence and would've happened around the same time frame regardless of the wheel/tire swap.
I mean come on GM....for an $80k vehicle, this shouldn't be my 7th related warranty item and 12th visit to the dealership in 3.5 months. (Just had to throw that in there so the my post would feel more related to the conversation at hand.)