I had a vibration in my 08 that we could not track down. It would start about a half mile down the road and then keep on going. As the tires warmed up they were going out of road force specs, the tech had to take my car out, heat up the tires, and then road force. One bad tire ruined the ride and it was replaced. My new car has the security package but I did not have the locks installed by our service dept. No vibrations yet! After hearing this I can see how it could cause a vibration, and with it not being connected to the rim or tire during balancing, no way to account for it? I will not be putting mine on, thanks for heads up!

 

no vibration at all.. then again my lugs are still in the trunk

 

I seems odd that the lug nut would cause the problem, even at 80 mph, since dynamic balance/harmonic frequency is a function of weight AND distance from the hub, and those lug nuts are practically right AT the hub. Glad you you were able to solve it.

I had my car for awhile before adding the locking lugs (I had the security package, but hd to have the dealer add the lug nuts). Noticed no issue before or after.

Then again, I am rarely above 65 mph since most of my life is spent on narrow rural back roads. I took it up past that once just to experience the tire chirp on the 3-4 upshift (it was...AWESOME!), but was intently watching for a wild turkey or other varmint in the road to foil my fun and not paying much attention to the vibration status.