Got my new Continental ProContactLS rubber installed yesterday, and just as it was with the Mercedes that I owned previously, these made a dramatic difference in the GT. Took less than a quarter mile to hear the difference, and once on I65 where there are some expansion joint bumps in the Bowling Green, Ky. area, there was a noticeable reduction in the feel of those bumps. I went one size larger with these to bring the speedometer a bit closer to true speed (always read 2 mph fast). Now, with 255/45-R19's instead of the 245's, the speedo, according to Garmin GPS and two GPS equipped Rove dash cams, reads just one mph fast. Now the bad news. While getting the new rubber installed, I was informed that the inner lip on one of the wheels has two cracks in it. No dings, dents, out of round, or any other obvious damage, just two cracks on the inner lip 180 degrees apart. Carfax on the car is clean, so not from a crash either. Anyway, Discount tire went right to work and found a used-like new wheel somewhere in New York that'll be here late next week, and is setting me back $360 w/shipping & tax, remounted and balanced. But back to the rubber. Long story short, these are smooth, quiet, ride better, the handling seems just a tad sharper, and they have a 70k treadwear warranty. If you are not looking to go with runflats, as I was not, I strongly recommend these tires, as does Tire Rack.