Tires: 1997 Oldsmobile Silhouette Sport with two different sized tires, oldsmobile silhouette, emergency maneuver

Question
I just recently bought a 1997 Oldsmobile Solhouette Sport mini-van from a friend.  I bought it as is, and that including the tires, 205's in the front, and 215's in the back.  I know enough about cars/suv's, to know that you can't put two different width tires on a car(and my struts were shot when I got them, which supports the reasons NOT TO).  
Now here comes my question.  The 215's in the back are in much better condition than the 205's in the front.  The call calls for 205's.  Could I put 215's on in the front, without messing up the car, or do I have to get 4 brand new tires, despite the great condition of the 215's?

Any help would be greatly appreciated, because my mechanic is insisting on changing all four tires, and I wanted a second(actually third, my grandpa is a mechanic and said it should be okay to use the larger tire) opinion.

Answer
Natalie,

Obviously, the best answer is 4 new tires. But that isn't you question.

I don't think you will wreck anything mechanically unless this is an AWD, but putting the larger tires on the front will tend to make the vehicle understeer less, and that's the more dangerous direction.  You probably won't encounter a situation where this would be a problem, but in an emergency maneuver, this might be the difference between spinning out or not.

But you might have some folks refuse to do this in order to protect themselves from legal action - and having a mechanic in the family who could testify for your side doesn't help matters, so don't mention it.