Hey KRyn, I actually do both track (Time Attack) and Regional Autoslalom. To answer your question, would also depend on the course you're on (lot or airfield), but also your final drive. I experience the same thing, and I found that with my 3.73 final drive, and keeping a 27" diameter wheel/tire combo, I tend to NOT hit 3rd on large airfield courses (unless the open up the course design), and in fact, spend quite a bit in 1st in tight parking lot courses, keeping within a 4000-6500 rpm powerband. I used to run a 26" diameter wheel/tire combo, often reached with 18" wheels and this often got me into 3rd or high 2nd in tight autoslaloms.
On track, keeping the 27" diameter was more ideal with my 3.73 final drive, so I needed to adjust my driving style for autoslaloms vs track. I used a gear calculator to arrive at my final wheel and tire choice 285/35/19 RE-71Rs. It gave me the largest selection of tires for a street-class vehicle and be competitive in both disciplines.
I was originally looking at 11" wide to accomodate 305 to 315, but wasn't getting the 27" overall diameter I was looking for, without only having one tire manufacturer as my sole choice of tires.