[Kracka]

When it comes to straight-line grip, to get a noticeably better amount of traction than your current tires, you're going to need some drag radials. The HTRZ III's are at the top of the Max Performance category; you could step up to Extreme but you'd be at <200 treadwear instead of your current 300, plus I think the only noticeable improvement would be during hard cornering i.e. track/autocross. My recommendation is to get two replacement tires and a custom alignment running minimal camber to maximize your contact patch going in a straight line.

After 12k street miles and 70+ autocross runs my Sumitomo HTRZ III's are going to be due for replacement in, I'm guessing, 3-5k miles. I plan on going with the same tires except in 245/40-17 instead of my current 235/45-17.