I have attached few pictures of my tires. Basically all four have the same issue, excessive outer wear :S I don't think its under inflation as usually both, the inside and outside tire walls would have been worn out, but its only outer.

 

Too much toe in in the alignment.

Or a very enthusiast driver taking fast curves. (the outer edge of the tire roll in under and wear faster).


With new tires you should get it aligned anyway so you will see.