My friend has in his GLi. He switched to 185/65/R15. Changed Alloys and Tyres. Hasnt felt any decrease in car's average. Ride is more soft/comfortable and those arch gaps are reduced. Car looks nice aesthetically. His car also handles rough roads,bumps and potholes much better than stock
I have an ATIV X - got it 5 days ago. I'm still on stock.
If you want to keep stock size then there is no point in changing the tyres. Drive them for 30-40k kms and then change. Change the tyres if you are open to moving to 185/65
I won't recommend 195s as that will reduce your cars average. 185/65 won't make much of a difference. At least it doesn't in my friends GLi CVT