I'll see if there are any studies on what a difference between 10 and 15 degrees sidewall angle causes in a performance application.

However, it also should be noted to any impact is very much tire specific, since the strength of a sidewall varies quite a bit per tire....with racing tires being very much on the high (stiff) end of the spectrum, and thus have less impact from sidewall angle differences.[/b]
Scot - On the Hoosier website, specifically on the page dealing with the care and feeding of the R6 tires we all know and love, I see a couple of statements that you may want to include in your research:

Wheel width dramatically affects wear and performance of the Hoosier P-Metric radial tires.[/b]
...and

It is possible to use narrower wheels, but at a sacrifice to shoulder wear and cornering power.[/b]