how important is it to keep the rear tire diameter larger than the front?

i would like to buy snow tires all four the same size so that i can rotate at least front to rear to even out the wear.

looking at 225/50X17 front and 235/50X17 rear but would like to put the 225 all around or even 215/55X17's. does this screw up the VDC????

 

DaveG, I talked with my dealer about all these questions and he recommended 225/55/17's for my A/T coupe with wheel package.(non brembo).
The front difference from stock is 3% slow, which didn't upset the VDC or anti lock, and the rear is about dead on, so no issues with VDC, Anti lock, or speedo.
I've got Yokohama AVS winter radials and they performed well for me. As you said they can be rotated front to rear.
G/Luck with yours.

<font color=red>GSM</font color=red> <font color=black>Silverstone Coupe</font color=black>

 

Last winter, i put 225/50/17 all around and i had no problem (Toyo) with the VDS, ABS and the TC.

You can try 215/55/17, but i'm afraid the rear rim is too wide (8 inches) for this size.