The more grip you put on your car, the harder it will be to drive at the limit. It will also wear everything on your car out faster (brakes, wheel bearings, shocks, bushings, etc.).
Also consider that the stock suspension was designed for stock levels of grip. Throw on race tires and the car will have more tendency to understeer. You have to modify the suspension and alignment accordingly to compensate for the additional grip. And when you have more grip then you are using your brakes more, etc. etc.
I've spent around 200 days at the track including 3 seasons of racing. I still have a blast on street tires when I go out in a street car. Less grip will teach you more at lower speeds and give you a chance to correct something that you might otherwise not be able to save. less grip = more learning
The extreme performance summer tires (RS3, AD08) are so close to r-compounds anyways that the difference is not that big.
I recommend a square setup on 18s for more neutral handling and the ability to rotate for wear. Square 18x9.5's with Hankook RS3 or Neova AD08, etc.
Last edited by smmmurf; 12-05-2011 at 04:52 PM.