Alicia,
Which tire is losing tread? If it is all four then there are some caster camber issues that need fixed. If it is just one, rotate the tires front to back and see if the problem continues. If you take alot of right hand turnes at high speed then your left front outside tread would wear more than the rest of the tire also, I've kinda had that problem. Check to see that the tires side to side and front to back are wearing even. Just my $.02