"Overall diameter can only vary front to back by about 5%" - is that to suggest that the Electronic Stability Program (ESP) is set such that it is always looking for a stagger?
Last year at The Dragon in the wet with leaves on the pavement running the OEM stagger wheels/tires setup, ESP only kicked in a couple times.
This year at The Dragon II we had gone to OEM rear wheels and tires on all four corners. Dry pavement, warm weather and ESP was insane!!
I take it that disconnecting the battery will not reset ESP?
Thus the only real answer is when driving aggressively, running a non factory wheel/tire setup, one should consider temporarily removing Fuse 11?
Yes, replacing the bicycle tires in the front has vastly improved the handling especially at highway speeds but the the overactive ESP can get your heart racing!
Regarding the 5% statement, the ESP is looking for wheel/tire combos that are nearly the same HEIGHT front to rear. Otherwise, the difference in circumference will cause different rotational speeds front/rear that are outside of the parameters ESP is designed to work with. The ESP will quickly go nuts even in normal driving and go into limp home mode if your front/rear tires aren't close in height - as some have discovered the hard way.
Now the issue of the ESP being more active in, um, spirited driving, with same WIDTH tires front/rear should probably be expected. The ESP programming is tuned to expect the typical understeering attitude induced by the narrow fronts. When you swap fronts, so that front/rear match widthwise, that expected understeer is gone or reduced greatly. The ESP is now compensating more in aggressive driving, especially when it's wet or there is loose debris that causes the rear to want to swing out. BUT, it's just doing it's job with the parameters set by the factory.
I run 195/50s front and rear and never see the ESP light in normal driving. But, under spirited conditions, it can become quite active. I did a hard drive on some wet backroad WV twisties a while back and the ESP earned it's keep for a few miles...