Tires: Tire Size for Rim Size, rim size, tire size

Question
I'm looking at mounting a 315 35 17 tire on a 9.5 x 17 rim.  It's for a corvette and I hear it will fit but it is not recommended, or rather it is not suggested by the manufacturer to go smaller than 10 x 17 rim.  What is the risk if any by doing this?

Answer
Wayne,

I think the situation is worse than you stated.  My book says a P315/35R17 should go on only 11" and 12" rims.

The risk is that the tire is going to "arch" and become directionally unstable - not to mention that the tire is going to wear very rapidly in the center.