In addition; the slightly narrower tire cuts through water and snow better. I find the Mazda has done an excellent job in picking a tire/shock/spring combination to achieve the excellent handeling. I would have no reason to change that. Ed
I just saw a CX-5 GT with 255/50/19 on stock wheels. The tire size is too tall for the vehicle and not my ideal choice on the stock wheels. The tire looked too big for the wheel but it's possible.
I went to 245/50/19 to get Michelin's but didn't want to run the wider tire on the stock 7" wide wheels.