If you're still running michelin super sports that's a 300 treadwear tire, you could keep the 255 size and go down to a 200 treadwear tire like a set of falken azenis rt615's or bridgestone potenza re-71r's. That would add some grip.
I'm still running the Michelin SS's. They're a decent tires, great on the road, but have their limitations on the autocross and road course (especially with 500+ hp). Once I lock down the fix for the tire rub issue, I'd like to switch tires. I'm thinking about offset shackles soon and if that's the case, I may even get new wheels so I have the same offset front and back so I can actually rotate tires. After this year, it's been pretty evident that I don't drive my car as much as I was projecting too during the build, so going down to a 200TW tire would also be in the cards with a 275/35/18.
