service stability system
 

I have an '06 STS at 75,000 miles. For a few months now the "service stability system" light has appeared. since then I have experienced hearing a wooing sound coming from the front left tire. in addition to that, i experience shaking at the steering wheel, gas peddle and even vibration felt through both the passanger and driver seats when I hit speeds above 55 mph. I try to pin point the exact speeds in which the vibrations occur but there is no exact speed. The shakes come and go at any speed above 55 mph. I also hear a cranking noise similar to the sound of an old door with bad hinges, that is coming from the front left when i use the break peddle sometimes. I do have after market wheels and tires on my vehicle. The tires are no less than 6 months old so there fairly new! I did call the service department about the stability system light and they assumed its coming from an error reading between the car and the after market wheels. But im more concerend about the shakes and noises im hearing! Any ideas before i take it in?? Thank you.
:confused:

Conditions may not be related. I suggest to deal with the "paint shaker" part first(re-balancing tires and check for worn parts). See if correcting vibration corrects warning message. If it doesn't you need to find out related code(s) and re-post.