Well, its not a danger to the driver, but it does pose a slight risk to the installer. I would probably have hesitated to install them if the job was given to me, when I was an installer. But, aside from danger, there are other issues when the tire is wider then the wheel's design intent.
A primary concern I have is that the tire will not be as stable under quick maneuvers, and also may "squirm" around while cornering. This is just simple geometry and the physics involved in it.
A secondary concern is unusual tire wear due to the sidewalls being forced closer together then they were designed to be. This stress can cause excess wear on the tire, and may cause premature failure in the tire's design (but I don't have solid evidence on this to show you when it comes to our cars.) This stress should cause the sidewall-edged tread blocks to feather or cup very quickly.
Again, these concerns may be moot, but I can probably tell you a lot more with close, accurate pics.