ESP light on at 85 kmh

I guess there are multiple possibilities that would cause the ESP to engage. I now finally found the cause for my problem. Everything works just find. ESP/ABS lights are off. Steering angle sensor was replaced a while ago. Then I read about different tires sizes, which made me check my tire sizes. Lo and behold my front tires are 225 and my rear tires 235. The tire shop had put on wrong-sized tires. A road test showed that starting at about 80 the front wheels turn faster by about 2 to 4 kmh, which will then engage the ESP thinking there is an imbalance. AWD needs the same speed on all wheels, except in curves but it is programmed for that and then you have the Yaw-sensor which will see whether you are too fast. So problem is solved.