C6 Grand Sport and Rolex Series Hoosier Slicks
 

I just picked up a 2010 C6 Grand Sport for the season and love the car so far!!. I would like to run the Hoosier slicks (Not A6) The second set of wheels are grey factory GS Speedlines in 18 x 9.5 and 19 x 12 with sensors.

The tires in question are 265/645R18's and 325/710R19's. Just so we are all on the same page these are slicks and size is not listed like the DOT rated tires are. 265 and 325 is the tread width in MM. 645 and 710 are the overall diameters of the tires. The 645 is very close in diameter to the stock 275/35/18 25.49" vs 25.6" and the 265 will fit on the 9.5 inch wide rim.The question I have is what issues will I run into with AH/TC with a
(27.95" diameter) tire in the rear that's 1.3 inches taller than the stock 325/30/19? It's kinda the same size as a 325/35/19 would be. I will run the car with the TC off. Other drivers of the car will not. Will that be an issue? I have found through my searches where a smaller diameter rear tire causes issues but can not find anything on a larger rear tire while keeping the front tire diameter comparable to stock. Any help would be greatly appreciated. While I am a bit addicted to the grip slicks provide A6's in the stock sizes are my second and fine choice of tire in any event.

After some searching and reading it looks like the computer will tell me there is drag on decel. I am curious if this will happen if even when the revs are being matched. I would guess the answer to be no. I will see. I am hoping that with TC/AH off I won't have any issues. I am going to give the slicks a try and see how they work. I am pretty sure the increase in corner speeds will outweigh what I would call a mechanical disadvantage caused by the taller rear tire.

As far as I know, the engine drag warning message is related with the traction control and does not even come up if you are driving your car in Competition mode (which disables the traction control, leaving the stability control on with higher tresholds). Since you're going to use these tires at the track, and if you use the car in all off or competition mode like most do, you should not have any issues.