Uneven tire wear due to factory lowering of car?

What is your question?

I have replaced my tires (full set) twice this year because I am told the factory lowering causes uneven tire wear. Life of tires has been about 15,000 miles and I am also told that is about as good as I can get no matter the quality of the tires. Also, can't rotate tires. Car is convertible with low-profile tires.