Potenza re040s have a treadwear rating of 140... of course theyre gonna wear fast.
Theyre made for gripping in corners, and have good traction, not quite drag radial, but close... it may suck to wear tires out fast, but if we didnt have some good tires stock, then youd lose most of the handling, and alot of the straight line grip we have.
You should get more than 6500, unless you drive on them very hard, which you said you do.