I raised this issue a while ago, but I'm about to actually purchase the new tires and I'd like to make sure. Have a 2014 CS with the original equipment 19" Goodyear Eagle F1 Asymmetric tires all around. Rears still have good tread on them, but it's time to replace the front tires. I've heard a lot of good things about the Michelin Pilot Sport 4S and I'd really like to try them, but the general consensus I've heard is: don't mix. My thought would be to eventually replace the rears with the Michelins as well. How really bad would it be to mix? If the tires are both similar in performance, what issues are we talking here? I realize the asymmetric tread might be something to consider. Wouldn't be doing any tracking. Any help would be appreciated. Thanks.