Now I have a theory that the VDC reaction to any tires other than stock is out the window. Here are my findings:

2003 Touring (w/VDC)
Stock Tire Diameter - 25.97" Front and 26.68" Rear
1st Set of 19" Tires - 25.48" Front and 25.26" Rear
1st Set of 17" Tires - 25.03" Front and 25.03" Rear

I have driven 5000 miles on the 19's and I loved testing the limits of VDC. ABS seemed to work fine in an emergency even in the rain. I put 255/40/17 Kumho MX all around on tonight and the drive home seemed normal to me. I haven't had a chance to drive hard with VDC on or test how the ABS reacts with the new tires.

With these sizes, and some reports from others, I have found that the following tire statements to not have affected the VDC:
The Difference of the Rear minus the Front Diameters must be within .2".
The Individual F&R tires must be within 5% of the factory size.
The Rear Tire Diameters must be larger that the front.

 

I changed tires, no problem. I changed rotors and it took a few days for the VDC to adjust. Then no problem. FYI.

 

Update: After taking some very fun onramps tonight, hard cornering at 60-80, VDC acted normal. I felt the front end want to understeer, VDC reacted like it should, I opened up on the steering a bit and kept throttling through the turn.

I must add - Kumho MX's are an amazing tire. They slip a bit when cold, but once warm they have taken me through turns faster than ever have attempted. Even under minor slipping, I have the confidence to stay into it.

 

Not true. The stock difference is 0.8" - nowhere near 'within 0.2" '.
That one goes without saying.

 

Sorry i meant to put .2-.7. Stock is 0.71". Also, I have driven on tires where the rear is slightly smaller than the front (19" tires)