2006 Kia Rio grinding sound while on drive

i have kia 2006 model its under waranty.past few days im experiancing some kind of grinding noise from wheels i have changed brakes 6monts ago,and when the car is on drive i can feel some type of presure and sound but i can apply brakes wiht out any distrubance, steering wheels is also very hard,and when on rough road i can hear a sound of wheels hiting pls advise me what would be problem.