I recently upgraded from the stock Stone Tires 225/f and 245/r to Michelin Pilots 245/f and 275/r.

When the roads are wet, I do not notice any difference when I turn VDC on and off.

I do not get the tire and exclamation point or slippery road icon any more either.

I can spin the tires and not get the icons either, where-as before this was not the case.

Do you think my VDC is even working? How can I find out for sure?

(The new tires are awesome, worth every penny.)

 

I think you answered your own question

VDC doesn't seem to be working because your new tires are so much grippier than your OEM potenzas... simple pyschology imo... you get grippier tires, your driving style stays the same, then the car will be a lot more planted.

If you want to find out for sure, go to a clear/empty stretch of road, rev the car to 6000-rpm and drop the clutch

the word "slip" will almost certainly appear (along with a whole lot of smoke )