I'm very new to the Porsche and to Panamera. I just came off several BMW as my car to drive. 2 days ago, I bought 2018 Panamera, and unfortunately, on the same day I picked it up. I found a severe damage in one of the front tires. I had to drive it slowly to one of the american tires, located 50 miles away, as it was the only store to have the tires size in stock. I bought two Michelin 275 /35/ R21 103y . The PSI system had error messages for almost 1/2 day, until it was able to calculate the pressure correctly. Just in case you don't know, it may takes times for PSI system to make its mind . Also my rear tires, are almost gone, any thoughts on good all year rear tires of Michelin ?