Traction ?
I like having the same size so you can rotate them around.
I would take a look at tirerack for the traction rating.
Look at the Kumho MX there pretty cheap 130 a tire or so.
Good Luck
if you really want to hook put a set of 255/50/16 drag radials on your stock 16's and believe it or not they will hook much better than a 315 sumitomo. when i say much i mean much, much, much better.

