Definitely fix the cause and worry about tires later. Check the struts, as those might be the #1 suspect. The front hub bearings go bad on those, but they usually cause a howling noise when turning the car in the opposite direction of the bad bearing side. No funny tire wear I've seen as a result; just noise and naturally an accident hazard if it decides to seize and fail. Secondly, if the tires weren't rotated on time over their life, they will cup anyway, no matter how good of repair the suspension is in. All the effort on trying to grind the tires is probably a waste, in my opinion. Just get a new set of tires... Even cheaper new ones are better than worn or cupped high-dollar ones. $150 should get you a set of good ones, if you have the stock 14 or 15 inch wheels.
Charles