I am having a tough time finding all seasons for my Quattroporte. The car is speced with 285/30/20 on the back. What do you think about going with 275/30/20 instead? They are many more types available in this size.

 

Michelin Pilot Sport A/S is a good choice.

 

I don't see any problem going to a 275/30/20. The only real difference would be the contact patch. At least going that route you will have more options available to you.

 

Even with the 275, Bridgestone, Pirelli, and Michelin are the only ones who have all season or winter tires in that size. Same with 285. You really only have 3 options.