Running 38-40 or higher all the time can wear out the center of the tire tread way too early (I did this on my old car w/ 205/50-16 Nittos).

I have Nankang EX-500 205/50-15 V-rated tires w/ 320 treadwear. After 25K+ miles total, 10K of that being lowered w/ 2.3 deg. neg camber in front, they still look like this: