2007 Subaru Impreza Tire Situation

[makky1]

I have a 2007 Subaru Impreza with 190,000 miles. I got a flat tire that couldn't be repaired and bought 1 replacement tire (my tires are new with less than 20,000 miles on them) The same model tire was discontinued so I purchased same size with 91V instead of 91H. I felt rushed due to work commitments when replacing my tire and was not able to properly research AWD requirements. And, although I really like my Subaru, I was weighing investing in four new tires with this mileage. I am looking for suggestions on how best to protect my powertrain. My commute is 30 miles each way - highway.