Originally Posted by BeBop86
Correct, that's what I'm asking.
What about sidewall strength? Wouldn't it be better to have a slight stretch on street tires to strengthen them up?
To strengthen, and provide a more responsive feel, generally yes.
I think that a wider tire will yield you a larger contact patch, thus better grip (and allow for faster times).
I'm sure you could calculate the break even point between a wider tire that provides more grip vs the slight loss of response. You could create a test to show how the variables (contact patch and responsiveness) have an effect on the result (time). Without actually coming up with metrics and testing this, my (slightly educated) guess would be that more contact patch and subsequently more grip will allow for fast times when compared to a slightly more responsive tire.
Alternatively, a proper sized tire for a 9" wheel will provide the best of both worlds (contact patch and responsiveness). I believe tire rack (and searching here on nasioc) will provide you with the best tire width for a 9" wheel. Keep in mind that the size can vary by manufacturer (Star specs typically run wide).