Just replace all 4 tires from Run Flats to regular F1.

Now at 53 mph my Active Handle turns on. WTF

Any Suggestions?

 

Were New Tires mounted in correct rotation?
Could be a Wheel Sensor connection that was disturbed during new tire installation? Use this to check them:

Codes C1221 - 1228 indicate that one of the wheel speed sensors is either sending a bad signal or no signal. Start by checking the connections. The wheel speed sensors are integrated into the wheel bearing/hub assembly pictured below. The wire coming out of the back is the connection for the wheel speed sensors. Verify that the connector are not broken, damaged, or corroded in any way. Pay particular attention to the female end.
The wire coming out of the wheel speed sensor connects to a 18" jumper harness, then to the main harness. It is very common for people to have a weak female pin in one of those connections. If all of that checks out good, Swap the jumper harness from side to side. For example if the left front is bad, swap it over to the right front. and install the good one from the right front to the left side. Then clear the trouble code. If the trouble code is now on the right side, you know the wire harness is the problem. If the code is still on the left side after swapping the jumper harnesses, you know the problem is inside the wheel speed sensors.

YOU should post any Codes you're getting from this A/H warning by doing this:
The "diagnostic display" mode is entered with the following procedure:
1. Turn on the ignition but don't start the engine
2. Press the "reset" button to turn off any warning messages
3. Press and hold "options"
4. While holding "options", press "fuel" four times within a 10-second period
When first engaged the on-board diagnostics go into an "automatic" mode which shows all parameters: PCM-TCS-RTD-BCM-IPC-radio-HVAC-LDCM-RDCM-SCM-RFA. If there are no problems, you will see "no more codes" on the ICP display. The computer will show two kinds of codes, "current" and "history," designated "C" or "H". A current code indicates a malfunction is present in the system whose module is displaying data. A history code indicates a past problem. When the screen displays "manual diagnostics," select the desired module by pressing the "options" button to go forward or the "trip" button to go back. Press "gages" to go forward or "fuel" to go back. To exit the diagnostic mode at any time, press "E/M".
If you want to erase or "clear" codes, press "reset."

....of course it's possible your EBCM is bad & needs repairing...but check above first & let us know. Bill T

 

Sounds dumb, but did you get the correct size tires for the fronts and rears?
A discount turd tried to put my fronts on the rears once till I informed him

 

Did you replace with the same stock tire sizes? If not, you HAVE to have at least 1/2 inch difference between front and rear height to have traction control and active handling work. The stock difference is 1 inch, but I am told 1/2 inch will work.

Go to tirerack.com to get height of tires you have.

Good Luck !

 

gpracer1 hit it on the head, they put the 18" tires on the drivers side and the 17" tires on the passenger side. WTF

Problem now resolved

Thanks!!!

 

OMG, how the hell did they do that?
If the 17's were on the left, maybe he wanted you to race in Nascar?
Glad you got it figured out.