I vote for big and badest hence the number plates BAD-ASP
I guess there probably is a point where the car is over tyred but remember the Cobra has a big proportion of it's weight on the rear wheels. The Lambos and Dodge vipers etc that run these tyre sizes don't seem to have a problem. The engineers that designed them would probably want the best performance out of the car.
I can imagine it might be a factor in understeer and oversteer characteristics. The grip at the front being overpowered by the grip from the rear.
Cheers