This happened to my 08 Legacy at 36K miles right before I turned the lease in..... Needless to say, I ended up getting 4 new tires. At that time, tires were around 50% (I religiously rotate them every 5K miles).
Good thing is, never tuned the lease in and sold the car to a coworker. Having 4 new tires helped with the sale a bit. Hopefully the same thing will not happen with the 3.6R